(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.)
-Jeweler's screwdriver (Philip's head/cross-head as well as flat-head)
-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.