Phantom Audio

Ok, I recorded audio into soundtrack pro, it was showing me levels, I could hear the audio by turning on the monitor and it showed that it was recording. When I went to playback the recorded audio, I couldn't hear anything, and it wasn't showing any levels bouncing, yet in the timeline there are waveforms. I'm assuming it's a setting that I've accidentally turned on, as it happened the other day to a file that was playing just fine only minutes before, but I don't know how to fix it. Help?! Deadline looming! Thanks.