Camera not working

Try booting into Safe Mode.

Check the Apple System Profiler to see if the camera hardware is seen. Option-click the Apple menu and select the first item. Click on the Camera item on the left pane of the System Profiler to see if the hardware information shows up in the right pane.

If the camera hardware isn't shown in the System Profiler, then you most likely have a hardware failure of some sort (Display or Logic Board) which will need to be repaired by Apple or an Apple Authorized Service Provider.