Why are my home key and back buttons not working?

The 3 bottom buttons including home button and return key are no longer working and don't respond. The power button is also not working. I have been unable to access the phone and hoped that allowing the battery to run down and then recharge would help but no. The touch screen functions work as does the slide menu at the top to access notifications. Very frustrating. Any ideas?

have you dropped or damaged your phone in anyway that could result in the buttons no longer working? have you tried turning the phone on and off - sometimes something simple like that can help.