For the simplest answer, reinstall Windows. You may also try this method. However, you will still need the Windows install media: (1) Enter safe mode (2) Run "cmd" from Start Menu (without the quotes) (3) Type "sfc /scannow" (without the quotes) (4) Follow the instruction SFC gives.
According to the manual, camera cable is connected to the AirPort card. I think If AirPort card is down, iSight would also fail since it cannot send back anything to the logic board. If iSight remains untouched, changing the wifi should bring both of them back. I also found Replacing iSight/Bluetooth/Wifi (cable only), which the camera cable and/or its connector causes the AirPort malfunctioning. You might want to check them too.