It sounds like the files are on an SD card. Are you able to mount the SD card on a Linux machine? You should be able to rename the file in Linux if that is an option.
BTW: illegal characters in windows file names include
- < (less than)
- > (greater than)
- : (colon)
- " (double quote)
- / (forward slash)
- \ (backslash)
- | (vertical bar or pipe)
- ? (question mark)
- * (asterisk)