This applies only to the Nintendo DS lite!
(See bottom for possible info on repairing an original DS.)

You may email me directly at my user name at gmail dot com--I would recommend this over using PMs.

NB: Read carefully: my text and the comments probably address all the issues you're likely to run into. Also, consider reading my original repair guide on the NDS (affectionately called the DS phat), as well as the comments on both Instructables.
Spend the extra time going over these instructions carefully: why jeopardize several hundreds of dollars in electronics with hasty skimming?

These instructions address how to:
-Replace the touch screen*
-Replace the bottom LCD screen*
-Replace the top LCD screen
-Replace the shell/hinges
Of a DS lite
(* denotes partial instructions: I didn't actually replace these, but I tell you how you'd go about doing so.)

Tools needed:
-Jeweler's screwdriver (Philip's head/cross-head as well as flat-head)
-Tri-wing screwdriver
-Pliers, if you are replacing the top screen and/or the shell
-Soldering iron, if you intend on replacing the top screen
-De-soldering wick or pump (useful if you're replacing the top screen, but not entirely necessary)
-A needle or hobby knife might be useful in prying off some of the rubber screw-covers
-Double sided tape might come in handy with replacing any of the screens.

You will be manipulating very small screws and delicate wires, and a soldering iron so make sure you are aware of what you're getting into. (i.e. If you have trouble plugging in the toaster in the morning, you may wish to reconsider this repair.)

Where to buy these components & tools:
-The top, bottom and touch screens will be cheapest on EBay. They will likely be shipped from Hong Kong, so it'll take two or three days longer, but it'll be a whole lot cheaper in the long run.
-Shell replacement kits are pretty common on EBay as well
**Note! If you want to swap the colors of your shell, be aware that the frame around the touch screen is part of the touch screen and will remain the same color, regardless of shell kit. (See photo.)
-Triwing screwdrivers themselves are not especially expensive, but you will probably have to look around in shops nearby, or scour EBay to find one that's reasonably priced--shipping charges are usually ridiculous. (Some sellers might include one in a shell replacement kit, so keep that in mind.)
Don't get too caught up in trying to purchase all these items from the same EBay retailer: buying all these items from the same retailer would have cost more, even considering the combined shipping discounts. Do some price comparison!

If you need help replacing the top screen on an original DS, refer to this set of instructions. If you are trying to repair the bottom LCD or touch screen on an original DS, those instructions won't help much, but I'm not too sure how much the DS lite instructions coincide with the original DS's.

Step 1: Opening Up the Bottom Shell

Start with the bottom half! Flip the console over, with the battery compartment at the right.

Remove the battery cover and take the battery out. There will now be a tri-wing screw in the bottom-right corner of the console (previously covered by the battery lid), as well as another two at the top-left and bottom-left corners. These are marked by black rings in the photo Unscrew these, and place them aside.

Helpful trick: grab a piece of paper, cardboard, index card, etc. and some tape. As each screw, pad and whatever little pieces come off the DS, tape it to the paper, and label it to help you remember where it came from (so you can put it back later!)
(Note: the photo is pulled from my other DS repair, so those aren't NDSL parts.)

Additionally: you may wish to work on a piece of plywood, plexiglass, or some other stiff, but portable surface. This will allow you to move your mess around without disturbing the components (but if you have a dedicated workspace, this probably isn't a concern.)

There are two rubber feet at the top of the console. Remove these to expose the Philip's head screws. You may find it easier to remove the rubber pads with a needle or hobby knife, but a small flat-head screwdriver works too. There is a third screw hiding in the Slot 1 bay, between the two that were covered by the rubber feet.

Spin the console around so that you are looking at Slot 1 (the hinge side of the console). Stick a flat-head screwdriver into the seam (see photo), and gently pry up.

The two shoulder buttons will become a royal pain if you don't remove them now. Take careful note of how the button, spring and hinge-pin are oriented for both sides before removing them. You may wish to wrap a bit of tape around each set of button-components, since they are prone to coming apart and getting lost.

The exposed PCB is held down by one screw, neatly circled in white on the board itself. Remove this.

Step 2: Careful With Those Cables!

Let me just begin by saying: these cables are the primary cause of errors, failed repairs and general headaches. You need to be very careful, and if there's a problem with any of your screens, it's probably due to a cable misaligned, improperly latched down, or simply broken by mishandling (most likely due to the repairer's efforts).
Go read the comments on my other Instructable on the NDS, most of them are bemoaning troubles with cables. If that's insufficient to warn you into caution, you'll well deserve any messes resulting from carelessness

Carefully open the console up, and push gently on the bottom screen to free the PCB. 'Flip' the PCB over, so that you can see both the bottom LCD, as well as the top LCD.

Watch the buttons! Putting spilled buttons back is fairly simple, but you might as well avoid it if possible.

Now, there will be two ribbon cables readily visible, and one more little one slightly hidden. One broad cable, and the little cable are for the bottom LCD, but the remaining broad cable is the one linked to the top screen.

If you are replacing the top LCD and/or shell: you will need to unlatch one of the big ribbon cables (the one nearest to the hinge), but leave the other two alone.

If you are replacing the bottom LCD and/or touch screen: you will probably want to detach the bottom LCD + touch screen cables, but do not touch the big ribbon cable that's connected closest to the hinge.

For unlatching the two larger cables: there are two beige plastic connectors linking the cables to the PCB. See the narrow black plastic bar lying across the ribbon cable? Carefully wedge your fingernail in, under the black latch, from the cable side and then gently pry up. If you use a screwdriver to do the prying, be extremely cautious not to damage the plastic, as any misalignment of any of these cables will render the console rather useless.
Refer to the diagram for a simplified illustration of this procedure.

For unlatching the small cable: Flip the PCB over so that you cannot see the screen, and turn the console so that Slot 1 (the hinge edge) is towards you. Slightly to the right of Slot 1 is a tiny cable connection (the cable is about 2mm wide). See the tiny black latch? You will need to carefully flip it towards you. You will probably need to use a flat-head screwdriver or tweezers.
Refer to the diagram.

Again: BE CAREFUL when dealing with these cables.

Step 3: Replacing the Bottom LCD And/or Touch Screen

If you are not replacing either of these screens, please proceed to the next step.

If you are replacing both these screens, you probably don't need to bother separating them. Just skip on down to the 'Installing new screens' paragraph on this step.

You should now have the entire bottom display detached from the PCB. Take careful note how the ribbon cables are oriented.
Now, look at the display edge-on. From the 'top' (touch screen) down, you should see:
-Plastic frame around the touch screen (this should be in the same color as the rest of the shell)
-A very thin section composed of several layers, maybe.
-Clear plastic layer ~1mm thick
-Thin layer of black adhesive (this is the separating layer between the LCD and touch screen)
-Metal cladding around the LCD

Wedge your fingernails directly above or below the black adhesive layer. (You may wish to leave the adhesive layer stuck to the screen that you are not replacing, but I personally pried them apart leaving the adhesive on the touch screen portion.)
If you are very careful, you can use a pointy thing, but preferably not a knife. A flat-head screwdriver might work. Separate the two, and toss out whichever one you intend to replace.

Installing new screens:
-Hopefully your new replacement screen(s) came with adhesive. If not, go find yourself some double sided tape. You may wish to double up the tape to form a thicker layer, but I'm not certain that's necessary.
-Stick the screens together, following the original orientation of the ribbon cables.
-Re-attach the cables gently, making sure to lock them in place.

If you are only replacing one (or both) of these screens:
-Plunk the PCB and screens back into the shell.
-Flip the PCB over and re-secure with the screw.
-Re-install the shoulder buttons (button, hinge pin and spring!)
-Replace the bottom of the shell, and re-attach with the 3 tri-wing and 3 Philip's head screws.
-Replace your battery & secure.
You're done.

Step 4: Removing the Top

This step is applicable only if you are replacing the top screen, and/or the shell. (If you are replacing just the bottom LCD and/or touch screen, you should have already finished your repairs by now. Go back to step 2 and step 3.)

You need to be looking at the plastic shell, under the bottom PCB. See two screws on one side of the hinge? Remove these. Now separate the two halves of the DS, but be careful not to damage the two wires and ribbon cable still connecting both sections!

With both halves disconnected at the hinge, feed the ribbon cable from the bottom PCB side, through the slot in the hinge, and gently pull the ribbon all the way through.
If you are replacing the top LCD, you can 'cheat' and simply cut the ribbon cable to bypass threading the end through the hinge. This, however, would be a terrible idea if you intend to continue using that screen.

Open the console up so that the top screen is exposed (you may wish to temporarily replace the bottom screen, etc. so as not to damage them). You will see four rubber pads inset into the plastic around the screen. Remove these (needle, hobby knife or flat-head screwdriver) to expose the Philip's head screws. Remove the screws.

Gently shut the console and turn it so that you are looking at the top (with the double Ds), with the hinge towards your side. The top of the shell does not pry 'up' like the bottom had, it must be slid open: there are L shaped sliders on the inside (refer to photo).
Insert a flat-head screwdriver in between the two halves of the top section, towards the center, and gently pry the case open by pushing the screwdriver handle forwards, away from you. As more of a gap is exposed, move your prying around evenly along the hinge and the top should come off easily.

It's somewhat tricky to get the screen up. If you are only replacing the LCD, you should attempt to leave the plastic cover in place, attached to the shell, and be very careful not to scratch it. A replacement LCD will not include a new plastic cover, but a shell replacement probably will.
I removed the screen by wedging in a small flat-head screwdriver and prying up, removing the screwdriver, re-inserting it, etc.
If you insert the screwdriver and then slide it from side to side, you will quite likely scratch the plastic screen cover
Now finish pulling the ribbon cable through the hinge to free the LCD from the shell.
Be careful, as the speakers are wired to the screen.

Step 5: Replace the Top LCD

If you are not replacing the top LCD, proceed to the next step for shell replacement information. (If you are only replacing the bottom LCD and/or touch screen, you are totally in the wrong place. Go back to step 2 and step 3.)

Take careful note of which speaker is on which side, and which wires are soldered to which pad.

De-solder the speakers from the LCD's ribbon cable. You can do this without a wick or pump, but I chose to use a wick.

The photographs documenting the de-soldering are 'staged': I was not about to try and operate a finicky camera + magnifying glass in a cramped space while waving around a hot soldering iron, so I substituted a pen. Use your imagination here.

Using a wick: heat your iron up, and place the wick between the solder and your iron. The copper and flux should suck up all the solder, leaving you with bare speaker wires and metal pads on the cable.

With the speakers detached, your LCD should be entirely free to be tossed out.

Take your new LCD and solder the speakers on to the appropriate pads on the cable. There should be tiny '+' and '-' signs at each of the four contact points. Just figure out which speakers should be soldered to which pair, and then match the red wires to the '+' pads, and the black wires to the '-' pads.
Use minimal contact with your iron: the cable is plastic and may melt if you are heavy-handed with your soldering!

If you are only replacing the top LCD, and not replacing the shell:
-Take the ribbon cable, coil it and then feed it through the small section of hinge. You will want to coil it such that the loop is towards the front of the LCD (refer to photos), and have it wrapped around the white & black wires that connect to the bottom half of the DS.
-If there's a film over your LCD, remove it now!
-Now you can stick your LCD back into the shell. (If you don't have extra adhesive, you can use double sided tape.)
-You have probably displaced the white and black wires that connect to the other half of the DS, and maybe your speaker wires are a little unruly. Re-position these.
-Slide the top cover of the shell back on.
-Replace the 4 screws holding the top half of the DS together.
-Re-stick the rubber inserts on over the screws.
-Re-fit the two halves of the console together, pulling the ribbon cable through the slot.
-From the bottom half of the console, replace the 2 screws holding the hinge together.
-Plug the top LCD's ribbon cable into the PCB and latch down.
-Re-secure the bottom PCB to the shell.
-Re-install the shoulder buttons (button, hinge pin and spring!)
-Replace the bottom of the shell, and re-attach with the 3 tri-wing and 3 Philip's head screws.
-Replace your battery & secure.
You're done.

Step 6: Shell Replacement

This is only applicable if you are replacing the shell!
Step 2 and step 3 address the bottom LCD and touch screens while step 2, step 4 and step 5 should get you through replacing the top LCD.

Disconnect the black and white wires from the Slot 1 side of the bottom PCB. Simply pry up on both jacks (a pair of very narrow tweezers, or careful prying with a flat-head screwdriver might work). The black wire can be fed under the Slot 1 bay, but use minimal force, and gently wiggle the wire around to free the cap from any snags.
Feed both wires through the hinge to free the top half of the DS entirely, and then continue pulling them through the top half's hinge to disengage the microphone (white wire) and WiFi antenna (black wire) from the shell.

At the right hinge (the one previously held in place with two screws), there should be a metal thingamajig that helps hold the console open/shut. Use your pliers to pull this out.
There is a 'C' shaped tube/ring/thing at the other side, remove this.

The following steps concern only the new shell, unless the old shell is specified.

-Place the metal thingamajig in your new shell.
-Take the ribbon cable on the LCD, coil it and then feed it through the small section of hinge that is part of the top half of the DS. You will want to coil it such that the loop is towards the front of the LCD (refer to photos).
-Now put the 'C' tube into the hinge so that the slot in the tube accommodates the ribbon cable.
-Stick the mic and antenna into your new shell, feeding the wire through the hinge, through the center of the coiled ribbon cable.

Now you can stick your LCD back into the shell. (If you don't have extra adhesive, you can use double sided tape.)
-If there's a film over your LCD, remove it now!
-If your replacement shell came with adhesive and a replacement plastic cover for the bottom LCD:
-Stick the adhesive to the LCD.
-Stick the LCD to the shell.
-Place the plastic cover over the LCD.

Continuing:
-You have probably displaced the white and black wires that connect to the other half of the DS, and maybe your speaker wires are a little unruly. Re-position these.
-Slide the top cover of the shell back on.
-Replace the 4 screws holding the top half of the DS together.
-Re-stick the rubber inserts on over the screws.

The top half of your DS should now be encased in your new shell.

Now you need to swap the shell for the bottom half:
-Take the inner half of the bottom shell (the piece that frames your bottom screens, and engage it with the top half of the DS.
-Re-fit the two halves of the console together, pulling the ribbon cable through the slot on the bottom shell.
-Before securing the hinge with the two screws, make sure your metal thingamajig controlling the open and closed positions of the DS is placed correctly:
Gently open and close the DS to make sure the alignment is right. If the console opens/closes at bizarre angles, adjust the thingamajig by rotating half of it with your pliers. (It's not hard to do hands-on, it's just hard to describe.)
-From the bottom half of the console, replace the 2 screws holding the hinge together.
-Pull the buttons out of the old shell, and put them into your new shell.
-Plug the top LCD's ribbon cable into the PCB and latch down.
-Run the white wire along the shell, under the PCB.
-Plug the white and black wire jacks back into place (the black wire attaches nearest to Slot 1).
-Re-secure the bottom PCB to the shell.
-Re-install the shoulder buttons (button, hinge pin and spring!)

Now, depending on the replacement shell you have, you may need to transfer some components from your old shell to the new shell. Place the bottom pieces from the old and new shells side by side and see what is missing from the new shell. Possible items are:
-Stylus holder
-Slot 2 metal plate
-A tiny piece of metal that the battery lid screws into
Most of these will come out and re-install with a simple Philip's head screwdriver, but the battery-lid-thing will require something pretty pointy to dislodge.

-Replace the final piece of the shell, and re-attach with the 3 tri-wing and 3 Philip's head screws.
-Replace your battery & secure.
Finally: you're done!

Step 7: Troubleshooting

Problem: The unit does not turn on, or turns on and immediately off again
Likely cause: No battery, or improperly connected cables
Solution: Put the battery back in, or check your cables

Problem: The bottom LCD is displaying funny
Likely cause: The associated ribbon cable is improperly connected
Solution: Check your cable again

Problem: The touch screen isn't responding right
Likely cause: The tiny little ribbon cable is messed up
Solution: Check your cable

Problem: The top LCD is displaying funny
Likely cause: The associated ribbon cable is improperly connected
Solution: Check your cable again

Problem: You broke a ribbon cable, or the connector
Likely cause: You messed up, big time
Solution: Cry me a river (and then go read the comments on my other DS repair guide)

Problem: The hinge isn't closing/opening right, or is acting funny
Likely cause: The metal thingamajig isn't configured right.
Solution: Fiddle with the metal thingamajig in the hinge. Pull it out, twist the sides a bit, try again.

Problem: Something I still haven't mentioned yet
Likely cause: I probably have mentioned it, you've simply missed it
Solution: Re-read the NDSL and NDS Instructables, and the comments

Problem: Something I really haven't mentioned
Likely cause: Weeeeird
Solution: Email me about it, nicely (It's my user name at gmail dot com.)