No solution, but another possible cause of the problem
I had this issue happen repeatedly on one computer a couple years ago. About half the time I would open a file, it would corrupt. After some trial and error I discovered the problem was the ram memory on the computer, not the hard drive or the reader or anything else.
If your memory isn't functioning correctly the computer seems to be loading the file into ram and then corrupting it even if you're not resaving or anything. I wasn't able to find any way to fix the messed up images other than having a second copy of them. Luckily I did (I'm a pro photographer) and once I figured out the problem it went away for years.
However I'm actually back on now because a different computer just did the same thing to one file... Thought I'd google it to see if there was any more info or a way to recover. Looks like things are still where they were a couple years ago. Crossing my fingers it was just a random corruption.