Nintendo ds lite touch screen protective outer layer(plastic)

Unless you are comfortable of taking it apart yourself and ordering the part online.
I'd suggest going here.
http://www.nintendo.com/consumer/repair/dslite_repair_home.jsp

The top surface of the lower ds screen can be replaced very cheaply. It's not the LCD screen, but the "digitizer" or touch screen.
You can get them on ebay for like $5:
http://shop.ebay.com/i.html?_nkw=ds+lite+digitizer&_armrs=1&_from=&_ipg=

If you don't have the know how to replace it yourself, maybe you can order the part and bring it to a repairman.

The bottom screen of the DS Lite is made up of 3 parts. The LCD Screen which provides the pixel images you see. The Touch Screen which basically is a piece of plastic that sits on top of the LCD portion picking up the touches from your stylus. And a protective shield layer, to protect from scratches. They are all glued together so unless you are looking, you would just think they were one screen.

If its just scratched up, you really only would need to replace the protective cover, because the Touch Screen and LCD Screen should be unscathed beneath it. However, if for some reason, you don't have that protective cover, or you just want to replace the screen anyway, you have options. You can buy the Touch Screen alone (attaching it onto the already owned LCD screen), or with a new LCD screen attached. As far as the protective layer, I haven't done enough research to know if you can buy them or not, but they do sell plenty of different kinds of screen covers that you can just stick on, which I am sure would be a fine substitute. My price estimate for the Touch and LCD Screens together would be anywhere from $5 to $20.

If you decide to replace the entire screen, I urge you to know exactly what you are getting into. Follow guides, know the parts, and have the tools you need. When opening up a device like this a lot can go wrong that you were not counting on, so take care.
When I fixed my own DS Lite, I found that it was very helpful to watch demonstration videos ahead of time, so I knew the steps, and when actually working on it, making sure I had guide available.

Here are some videos and guides you can look at to make sure you know what the project entails, as well as how to go about it:
http://www.youtube.com/watch?v=fJ3W6Y9zTQY
http://www.pwn3d.us/archives/440/
http://site.powergamingparts.com/RepairNdsl.html
http://www.flickr.com/photos/retroleum/sets/72157605949769269/ <-- This is more for just extra reference pictures

There are probably better guides out there so do some research on your own as well.
I hope that helps.

If your touch screen appears to be working but does not calibrate it can sometimes be something stuck on the screen, including a screen protector. Have a good look and maybe remove a screen protector and put a new one on. Sometimes a bit of dirt get trapped under them. Or a big scratch, which basically means a new touch screen.

maybe the touch screen is defective. did you drop the DS somewhere?

if you do the calibration REALLY fast, it may be able to correct the problem

Well, did you call nintendo to see if you were under warranty?
why did you try? do you have a degree in engineering? Regardless, now you have voided your warranty. Call them and see.

If it was me i would of found a repair shop, because id be too afraid of breaking it, but do handle with care, as you already know they are not cheap.

Jack

contact www.ConsoleRepairsDublin.com

Two choices. One: If your console still has a warranty, send it in to Nintendo for repair. Two: Search on some site like Ebay for replacement touch screens and buy one. Replace the faulty touch screen with the brand new one.