Apple Logic Pro /LogicExpress Discussion

I have a 2-track recording of 90 minutes of dialog, with one  
conversant on track 1 and the other on track 2.  While futzing around  
with strip silence today, I went to the undo list to undo all my cuts  
and strips, and got a bunch of error messages about the Audio  
window.  So I shut down without saving, and now when I load the song,  
both audio files are the same conversant.   The file names still say  
"subject 1" and "subject 2," but the "subject 2" file now looks and  
sounds like the subject 1 file.  I have tried loading them into a new  
song and rebooting the computer, but the audio file is still wrong.

Does anyone know a way I can get the original file back?  I never  
deleted anything - the file just magically changed.  If it's a  
problem with the header information (both files are BWAV) then maybe  
there is a really low-level audio analysis tool that can recreate the  
original?  I'm stretching here, but don't want to have to repeat the  
experiment.

Thanks,

Gregory