? lost files?

I lost some files in a hard drive. I was able to recover most but I got a bunch of files that show a size and file number but will not open anymore. All of these files were taken with the new canon 7D. I was told that they are large jpg files and if some of the data is corrupt they will not open... I talked to the sandisk people and he says if it is showing the size volume there should be a way to open it? any ideas before I throw in the towel.
thanks,

You could try adding the .jpg extension and see if that helps -- otherwise you will need image recovery software to try to get things back in shape -- try a google search for "image recovery" (aside from suggestions from here).

Sandisk has recovery software that comes with their cards, but it may be card-specific. Did you discuss this software with the support person? If it only works on cards, you could copy the files onto the card then run the software on it.

Was this done while the files were on a card or from downloading from a card? If so, I'd run some stringent tests on that card and even then wouldn't trust it for "serious" work. In fact if it was mine I'd trash it unless I was totally short on funds/cards.

In the past I have found Irfanview capable of opening files that wouldn't open elsewhere, even identifying them as jpgs even though the extension was missing. Once opened you can resave them and they will be normal. Irfanview is free, so it's worth a shot.

Are the originals still on the card you used? Am.