Phone troubles

Ok. Right. I have a sony ericsson w580i and its like, screwed. The back, left select button and the up button do not work. It has just happened out of the blue not due to any damage. Every now and again they will work for like 5 mins but then will break again. Anyone who's good with this sort of thing pleeeaaase like, help? If I dont find a way to repair it I will take it to the shop but im pretty much skint so I cant really afford to do that. Anyway im rambling so yeah - basically, any ideas?

Xxx

allot of people including me are having phone troubles from at&t to Verizon it is all n\messed up now