The Logic Off Topic list

greetings,
I am a new logic express 7 user, about a month now.
I had been creating songs/tracks with mostly loops and 
some voice and audio samples that I had made.
I was working on my largest composition so far 
and didn't freeze anything and the program crashed my computer.
Since that time I have not been able to get any sound out of logic.
No new apple loops, not any of the vocal samples I had put in. 
All of teh compositions seem to still be in tact but there is never 
any levels going through. Nothing is muted or solo'd.
I know I need to spend some more time tracking but last night after 
about an hour and a half in logic then an hour in the manual I 
through my hands up in disgust and defeat. 
Any troubleshooting ideas would be greatly appreciated.
I was hoping to incorporate those loops into my weekly d.j. set 
tonight but at this rate it doesn't look possible.
tschuss
AWN