If the only copy was on the hard drive that crashed, there isn't much you can do to get an origional copy. I would look at the log version of the data file to reconstruct it. The difficulty will vary according to the complexity of the input file (e.g., due to the application of multiple randomization functions). If have any specific questions about how to work backwards, please let me know and I'll try to help in any way I can.

-Blair