Lost Audio

Please help! I was editing a 35 min file in audacity and when I tried to hit command r, as I had been doing over and over while cleaning audio. I think i hit something else because all of the audio disappeared from the track. I tried to undo and i have a little close message next to my redo button. I have no idea what I did to lose the audio, or how to retrieve it. I may have hit command E.