I just saved over a thousand pictures using the procedure described in this question. However, a few of the pictures have grey areas on them. the thumbnail displays the picture perfectly, but once viewed, the picture contains this grey block. I've tried Irfanview, which didn't help. I've also tried photorescue, which did kind of help, but, requires a key, that i tried to find on the net, but all have expired.
Is there any way to recover the lost JPEGs?
If it's an option to retry the recovery, try using PhotoRec to recover your files. It is a companion program to the TestDisk data recovery software. I used it, and it works wonderfully -- I didn't see a single corrupted image that it recovered, and it recovered more than Recuva did did.
The gray squares are actually a symptom of a corrupted jpg file and can't be repaired. The reason the thumbnails are still fine is that, depending on the file type, the thumbnail is stored in the picture and is not corrupted, so it still displays fine.
