Have you tried reading it on a different computer? I’d try that first to make sure it’s not some sort of malware infection or hardware issue on your current computer.
When none of the computers you’ve tried can read the file names properly, the reason is that all of them are going to the same place in the Master Boot Record (MBR) of the flash drive. All hard drives have a kind of table of contents of all their files, folders, and subfolders in the MBR. If it has become corrupted, then it can’t tell anyone visiting (i.e., the query from the operating system) what’s there. Norton used to have as part of the Norton System programs one that would try to fix the MBR. See what you can find at shareware depositories (Tucows.com is one I know of off-hand, but there are many others) in a utilities section that can fix broken MBRs.