Hello Turok.
It looks as if one of two things happened here.
1: The information was never properly written to the card, in which case its lost for ever.
2: The information was written to the card, but now the PC cant read it properly. If this is the case, you could try using something like File Scavenger to try to recover the data.
The reason you can see the thumbnails but not the whole image is because usually the thumbnail is not part of the main image itself. Its written separately in a different part of the file which apparently has not been damaged.
Good Luck
