Able to retrieve audio?

Hi!

I recorded an hour-long presentation, but for some reason, the audio only picked up outside noise, not from my actual computer (i had the headphones plugged in) and they're not showing up as separate tracks. i SUSPECT i only had "system audio" checked when i recorded and not the "macbook pro" option selected.

is there a way to retrieve the audio from my mac? this presentation is no longer available at all so this is our only chance to get it back! :(