photo booth camera not working anymore

This is on a Mac, right? (Is Photo Booth on an iPhone or iPad? I'm not sure.) What model? What OS?

 To narrow things down, try these steps:

• Restart the computer (of course)
• Re-start in Safe Mode. This bypasses certain potentially disruptive processes. Safe Mode is different for different computer models, so see this: 

           Start up your Mac in safe mode - Apple Support 

• Make a new user and see if the same problem recurs with it

One of these steps may fix the problem, but their failure to work also helps figure out what's happening.

minglebells wrote:… i tried what you said but can't find 'safe mode' anywhere

I included a link for instructions on booting into Safe Mode.

           Start up your Mac in safe mode - Apple Support 

I see that you have a 2014 intel iMac, but you didn't say what your Operating System is. How much free space is on your hard drive?

Of course it is-- I'm blind, apparently, to big letters…