Question : I is it possible to fix a corrupted .dat file?

I hope I am posting this in the correct area, because the file isn't really in a database like Access or SQL or Oracle. If anyone can answer this, I will be forever indebted. Here is the problem.
 
On our server we run Medisoft which contains two programs: Medisoft for billing (extremely important) and Medisoft Office Hours (fairly important). We have multiple backups with tapes and standalone backups from the system, but unfortunately our tape backup of the server broke last week. We are still waiting for out IT department to install a new hard drive back up program.

All of our work stations and server have UPS Backups so when the power went out today, I am not sure why when each computer was shut down properly, the ohapp.dat file became corrupted. Maybe it's because our APC UPS Backups don't have the SmartUPS which allows a constant source of power to the PC, not just a surge protector.

Anyway, the Medisoft Billing data file doesn't seem to get corrupted while the Office Hours (the program containing all of the appointments for the next year) does. I do have a backup from last Friday so I won't lose that much data.

My question is can I fix that ohwai.dat file that is corrupt?

Thanks in advance for any help. I guess just a no you can't would be an answer as well, although it's one I hope I don't get.

Answer : I is it possible to fix a corrupted .dat file?

It is possible that previous versions from before the last time Medisoft wrote to the file are still around, or better yet, you may still be able to get to the supposedly corrupt file provided it has not been overwritten.
The only way to get at those files is to use data recovery software. Get WinHex http://www.winhex.com/winhex.zip and then run it. In the program, select the drive where the file would have been stored, then on the menubar, click tools -> disk tools -> file recovery by name then in the window enter ".dat" without the quotes and click enter. If your .dat file is found, it may not have the same filename as it did before, so you'll have to check each of the files found, although size will be a good indicator.