My nokia 5310 phone keypad isn't working. how to fix it?

[GbemilekeOnashile]

Hey...i just got my phone back from a friend who helped me fix it and after sometime the keypad stopped working. The music keys still work though but the others don't. Is this a software or hardware problem because he reset the firmware of my phone? Is there anyway i can fix it myself? Would it work if i flashed it? Please help.