Sound effects and music have been working just fine but suddenly all my sound effects and music files are silent. The wave forms are still present but the audio meter says negative infinity. When I click on any point the meter registers for a very brief moment but no sound is heard. Furthermore, I can hear new sounds and music from the FCP menu but once I add to my timeline they go silent as well.

I have closed out FCPX and restarted a number of times, checked individual volumes but don't know what is the problem. Can anyone offer some advice?

~Burton

Sounds like you have the one of the little buttons clicked. There's a solo button to hear things on their own, you might have that selected for one clip in your timeline so everything else added is turned off. Trust me, it's one of the little buttons. If not the solo button, another one near by. It also has a keyboard shortcut which you might have inadvertently triggered.

Command-S is the default shortcut for Solo mode.