If your phone functions fine apart from the LCD (you can make/receive calls) then it's most likely that the LCD is at fault and a new LCD should solve the problem

All online stores, in the UK at least, have to offer a 7 day cooling off period by law, so if you bought a new screen online and fitted it but then found out that it didn't solve the problem you could send it back for a refund

This place has them for £65 (free delivery and free fitting instructions): http://www.formymobile.co.uk/proddet...p?prod=p800lcd

This place has them for £69.95 (free delivery): http://www.solware.co.uk/mobile-phon...son-p800.shtml

& this place has them for £64.95 (+ £1.95 delivery): http://www.blueunplugged.com/Product...aspx?ptnrSrc=2