Recently, I had a problem with my Nikon D70. Over 4 years of use without any issues and then the CF card reset without any warning. Some important pictures were gone. Or so I thought. I was not happy.
I came across this Lifehacker post Five Best Free Data Recovery Tools and gave Recuva a shot. Problem solved. The price was right too (free). It recovered the lost pictures on the card as well as several from years past. It also works with hard drives, memory cards and USB drives. Happy again.
If you find yourself in a similar situation, try Recuva.