Garage Bang experts needed!

I've had my mac white for a while and have been successfully recording music with it, up until about a month ago when nothing i played or recorded was being projected through the speakers.
EVERY indication of the track being played and volume on was affirmative but still no sound came out, yet all the other non GB sounds worked fine
all levels were up, no track was muted

but! when i had my audiobox NOT PLUGGED IN the sounds came through fine, but upon plugging in the unit that changed to silence. Even tracks made without the use of the audiobox are now rendered silent

i'm in the middle of recording a demo and needless to say this is more than inconvenient

thanks in advance!

Go to the Midi Application under Applications>Utilities. Check to see if the input is set to your interface (Audiobox), and the output is set to Built-In System Output. THEN, go under preferences in Garageband, go to Audio/Midi tab, and check to see if output is set to system. Do this WHILE you have the audio interface plugged in, and do step 1 with Garageband off.

You can also use the line-outs if your interface has them, and plug those into a good set of monitors.