Aarggh, looks like you corrupted the images on your card
You could try copying the files over, manually, using the Finder and see if that works. If that doesn't work, you may be able to recover your images by using card recovery software.
Hope this helps and good luck!
Hayo
P.S. As Kirk and others always tell you: NEVER EVER work on files on your card directly, but first copy them to your computer. I'm afraid you found out the hard way why this is