You'll first have to be sure of whether or not it is a software or hardware issue.

First step obviously doing a hard reset of the device. Second, try reloading the OS.

If the problem persists, it's probably hardware and, in that case, you are probably best off to do a backup of everything on your phone and find another 9700 to buy. The price is probably cheaper to replace than to have a repair shop try and fix it.

PS - the 9700 rocks and I don't blame you for hanging on to your investment!