Can't unmute my iBook G4

Today I started up my computer and the audio won't work. When I press any of the volume buttons the grey volume indicator appears, but won't let me change the volume. And there is a circle with a slash through it below the volume indicator. I tried system preferences to see if it had been muted there and it won't let me unmute it - everything is grey, including all the sound effects (and I can't change those either). When I use iTunes, I play a song and it says it is playing, but the counter doesn't proceed. Any ideas?

Figured it out!

All I did was turn the volume control off in the menu bar and restart.
Fixed the problem.