Before answering you question could you please tell me which cam you are using i mean which company's.

The problem with you is that the utlity that comes with driver si not working.

Either you just move around the boarders of the screen may be you can see a pop up which is the utlity for the camera.

other option is go to device manager and disable the camera. Then, enable it.

other option is to Bring up Quickplay, click on camera and movie real icon then see if your camera is listed. If it is just double click on that and your camera should work