Hi,
What was the size of the original files?
In a JPEG there are actually two photos, a small one up the front (used for the thumbnail preview) followed by the larger full size photos.
It is possible, if they are large files, that the full size was not being recovered.
Let me know the original size, and also try opening the files with
IrfanView - Official Homepage - one of the most popular viewers worldwide to see if you can see any of the full size image.