built-in iSight camera, microphone, speakers, and USB ports on the display are not working!

built-in iSight camera, microphone, speakers, and USB ports on the display are not working in my LED Cinema Display 24-inch. They just stopped working. I'm not sure what the problem is.

Yes I made sure the USB cable from the display is firmly plugged into the USB port on my computer.

Any other suggestions? Is there a software that I need to install? An update? A firmware?