This is the reply from one of members re restoring a corrupted file

The techs at Microsoft were able to restore the Excel file!

I'm not sure what all they did (some of it was magic, evidently), but here's a tip they passed along.

If you're having a problem with an Excel file, save it as HTML (which is one of the file types in Excel), then save it back to .xls

They say that will often recover lost information, or restore a corrupt file.