I have had great luck with "Photorescue Wizard", you will have to pay for it, the trial will only do a few pictures, but it works great and everyone should have a recovery program. I think it's $30, here is the site.
Do a Google search for "disk recovery" or "flash card recovery" or "memory recovery," as there are several good programs out there. A year or so ago when I had a problem with losing an image, I was able to recover it by using the trial version of a program. It was on a PC, and now I can't remember the name of it, but at the time I did notice that there were several programs available for just such emergencies.