Hi Robert, Is the device powering up ? When plugged into power or computer you can hear it chime or vibrate? There is no one solution to fix any problem, we'll have to gather more info to find the culprit/ problem .
As others have stated above, in most cases it's the flex cable, if that is the case just replace. But if your like me and enjoy hot swapping parts ( very dangerous for the health of the parts being swapped) You'll simply need to restart the device. From my testing I noticed that the camera and earpiece don't register until the device is restarted. Sounds so simple... but it works every time for me!
