Before you junk it and buy a new one, have you considered buying a new screen?
The simplest way is to buy the combined screen and "digitiser" package (the digitiser is the touch sensitive bit).
If you buy them together, then swapping it over only requires one ribbon cable to be plugged into the main circuit board.
There are usually plenty of adverts for them on eBay, or if you add your location to your profile (or just tell us!) someone may know a local supplier.