the wheel doesnt seem to work the resst of it is ok
the wheel probably lost its calibration somehow unless you beat up it really bad.
- try turning hold on and off making sure not to touch the wheel while doing so. this will recalibrate the touch sensitivity.
- if that doesnt work, try pressing the center button and the menu button at the same time til the apple logo pops up then let it reload.
- if that doesnt work and the wheel is physically broken the part only costs a couple bucks on ebay and its a pretty easy fix
if you have warranty go to apple. if you dont they will probably rip you off if you go there for a repair