What happened to my volume control?!

[averin]

My volume control
- shows up in gray on the menu bar
- won't go up or down
- the same thing happens in System Preferences but the Mute button is not checked
- sound does not play
- when I use the keyboard to change the sound, the null set sign appears beneath the volume bar and the speaker again appears in gray instead of black
- still does not work upon restarting

Why might this be? (Thanks!)

 

[averin]

Well, this is weird. I took out my headphones, restarted, then put in the headphones and everything worked perfectly. I still have no idea what happened but it works now so I'm happy.