Formatting is a liast ditch effort, but it can work. One problematic card I had went like this: My friends took it to the photo place, and they said only five photos can be recovered. I ran it through three different recovery programs, and got the same results–only five photos. However, one of the recovery programs generated about 300 recovered images, although they were the same five images repeated over and over and over. One of the other ones, I noticed would seemingly jump from about 2% or 3% finished to 100% without all the points in between.
On a hunch, I decided to format the card. The recovery still issued the same problem. (A format doesn’t actually erase much info on the card itself–it just rearranges the directory so it tells the camera, computer, etc., that memory locations can be written over. ) I shot through about ten photos–past wherever the first five files would be stored, and ran it through the recovery program. Whammo. That did the trick. When I ran the recovery program, it found about 300 unique image files this time,
Another bad memory card that was having difficulty in the computer wouldn’t generate any results with the recovery programs until I formatted over it. I do photography for a living, and I’ve had three cards go bad on me. I’ve been able to recover about 99% of my photos (never lost an important photo) and in two of those three instances, the recovery actually involved a format of the card.
I mean, take it for what it’s worth. You’re free to not believe that formatting the card worked in my case, but it’s saved my ass twice.