A similar problem occurs when you try to copy backed up files from pc to usb.
I keep all my SX700 usb folders on a 2Tb external disk drive. But I learned some time ago, it's not a good idea to try and copy them to a new usb stick all at once.
If you do, Quite simply, Windows can't cope with it, and gets very confused.
Yes, I KNOW I've got sub folders with say Pop and Rock in 3 different main folders, and that's how it works... and yes, thanks Nanny Windows but NO I don't want you to overwrite my files with the same name, because, actually, the Styles are different.
I've found that the only sure fire way of copying a usb stick is to do it one folder at a time.
Sure, it takes longer, but I get a clean copy, and I put back exactly what I want.
But all this assumes, of course, that you have backed up ALL your files.
You have, haven't you?
Losing them all to a faulty usb stick would not be good So back up your sticks... Regularly!