popatim :
I would think that a 64gb sd card would still be under warranty as well as being a prime candidate for scammers to fake."
Thanks for the suggestion but these solutions don't seem tom apply. I've been using the card for more than a year and have reached a point where only 10GB remain open. When I tried to sync another GB of stuff, it didn't show up so I decided to reformat and start over. That's when I discovered it wouldn't reformat so I used a card reader to delete files. However, there are two apparently corrupted files that won't delete and don't want to let me delete anything else either.
Thanks for responding though. Any other ideas!