I was messing a little with the files on the SD card trying to do something, I forgot making a backup and when putting the SD back it said "data corrupted, format SD card to continue". There was nothing really important in it, and since I didn't have a choice, I did. I redownloaded everything including Nintendo Letter Box. However, when I try to enter, it says "data corrupted, delete extra data to continue". Problem is, there is no extra data :\ What can I do?