Why wont my buttons work?

hard to tell, anything happend to the iPhone ?

is the complete touch screen area dead ?

if the phone wasn't dropped or anything like that, i would first try to make a hard reset (press and hold the home and the sleep button until the phone restarts - if that won't help, i would disassemble it and check all connections on the logic board.

choose the step-by-step guide for you iPhone generation on the right side, the needed tools are listed in the guides.

if the connections are ok - the digitizer of the iPhone could be defective and should be replaced