Photo Booth says "Camera not connected"

Hope info from this article is helpful.

http://support.apple.com/kb/HT2090

Reset SMC. http://support.apple.com/kb/HT3964

Choose the method for:

"Resetting SMC on portables with a battery you should not remove on your own".

Best.

OK, I've got this problem, Macbook Pro Retina 13", now running Yosemite, but same problem on previous OS.

I've tried: Resetting PRAM, SMC, Restarting in safe mode and resetting permissions.

Also done the sudo killall SMCAssistant thingy (searching the computer finds no such file anyway), and logged in as a separate user.

System profiler does not recognise the in-built camera, not even after a restart.

Any ideas? I've been working on this problem since I discovered it several weeks ago (I don't use the camera very often, so no idea when this started)