[Ger-Poland-Volhynia] Sort of OT - corrupted file of genealogical material

[F&RM Haddad]

I'm just devastated - the file in my genealogy program that held over 8000
names (I record siblings and spouses of siblings, etc., as  well) is
corrupted, and I cannot access it. Last night I tried to do a merge, and the
program froze. So I had to shut down the computer - and when I tried to
access it this morning, I got the following error message:
 Error opening database.
Unrecognized database format 'C:\(genealogy program)\Data\My Tree2.fdb'.

I'm very carefuly to back-up every time I finish with the program, but of
course couldn't do it last night. I've tried accessing the file directly,
and still get the same error message. I'm not terribly computer literate, so
I tried the old standby - re-booting, and no change.

I have an old file that still works, but there is easily more than a hundred
hours of research and data-input that is not in the old one, but is in the
one I can't access.

Any advice gratefully received - (privately or here) as well as advice on
what to do so that this doesn't happen again. I can't afford to lost that
much information. Help!

Rose-Marie