Now's a great chance to set some ground rules for what to do with code in the future to keep this from happening again. Even if you can recover the compiled code, that won't help you if you need to tweak something later.
The most robust option is to use a source control program such as subversion to keep track of the code and versions. You can read a lot about it and other source control programs in the following thread:
http://www.chiefdelphi.com/forums/sh...ad.php?t=70880