I know what you're thinking and you are right, I'm an idiot. So I took some senior photos for my niece and was editing in adobe bridge and yes, I did a batch rename to a lot of photos in their raw format on the memory card. All of the thumbnails are now black and say "exec" in bright green:
When I double click on a thumbnail I get this:
Please tell me they're not lost!! Thank you!
And I see exactly what went wrong. I own a Macbook.
If for example your raws are from a Nikon camera, the file extension is .nef DSC0000.nef for example.
Remove the .nef, OSX does not know what it is and gives you that exec thumbnail and also can't find what program opens it.
Solution: rename the file with the proper extension and you will see your raws again. Unharmed.