Looks like they sell the parts [http://www.yallstore.com/lg-gt505-lcd-screen-tools-p-39250.html|here], [http://www.360batteries.com/lg-gt505-lcd-screen-display-replacement-tools-optional-retail-new.html|here] and [http://cgi.ebay.com/NEW-OEM-REPLACEMENT-LCD-DISPLAY-SCREEN-LG-GT505-/120481476508?cmd=ViewItem&pt=UK_Mobiles_Accessories_RL&hash=item1c0d416f9c#ht_1547wt_991|here]
I can't find instructions separately but they may come with the screen and you should ask them.