Photo files are there, but photos aren't..??

Ladies and gents,

I had saved some digital photos (jpegs) to a folder in mid-summer. Had viewed and edited them a few times w/out probs. Now, when I try to open the files (with either Dell Image Expert, Photoshop, etc), the files are listed as being there, but there are no photos. Foe example, when I try to open with Photoshop, it says "Could not complete your request because a JPEG marker segment length is too short (the file may be truncated or incomplete)".

Any idea what gives, and if these files are recoverable?

Mucho thnx!

David