We've all been there...you accidentally press the "delete all" button on your camera rather than just deleting a single photo...or, your photo card gets corrupted! Both have happened to me, and the one FREE program that has done wonders in recovering my data is called PC Inspector Smart Recovery.
If you are interested in downloading the program, you may do so at this reputable site:
PC Inspector Smart Recovery (downloadable from CNET)
For some reason, some Vista operating systems have a runtime error when you attempt to launch the program. The workaround I have found is to right click on the program icon and click "Run as Administrator." Just another one of those Vista glitches.