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I always thought in Unix and hence Mac OSX once a file is deleted and then emptied from the trash it is gone forever due to the way Unix allocates and used hard drive space.🙁
 
No, the space is just marked as being available for future writing.

You need a program like Data Rescue II to see if you can recover anything. Also, don't write to your hard drive if you can help it until you determine something can be recovered or not.
 
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