Well, if you have a USB, flash drive, etc. you must have extra copy from the laptop, computer, or cellphone, before you insert the USB, be sure you open the firewall, or if you didn't have firewall be sure that the laptop or the computer is free from any kind of viruses such as TROJAN HORSE virus. The only way to recover is to see the USB file, if it's empty but have a memory search it from the right side up of the file. because sometimes it was hidden or hide files meaning not corrupted not affected but have a virus always click the eject DO NOT REMOVE without being clicking the eject. that's it I'm a I.T by the way if you want to ask something the do not be afraid to ask me.