You can either carry on with the cracked screen or replace it. If you are a capable repairer, you can D.I.Y. (screen suppliers often give on line directions on how to replace a screen) Screens can be bought used for £30 or so or new for £60+. A shop repair will be £100+. Screens are normally fixed with several tiny screws top bottom and sides, but this varies. Also there's is a 30 pin connector at the top (data) and a 2 pin connector at the bottom (backlighter). All screens have a part number marked on the reverse side and a Google search will reveal availablilty. Firstly you'll have to CAREFULLY remove the screen bezel- if it won't come off it after you remove the little rubber plugs and the little screws, then there are still screws or clips attaching it, bezels are very thin and easily broken!
Helpful Harry, February 2011