Sometimes due to virus attack, our pen drive data is hidden. We think, all folders are deleted. So, check first before you format your Usb otherwise you will lose your data forever. Sometimes hidden files are not displayed even if you “Show hidden files and folders” in the Folders Options. To find hidden folder in your pen drive. Just run the following command in your command window.
attrib -h -r -s /s /d g:\*.*
For accurate command just copy the above command and pest it. Here g: is considered your pen drive. Replace g by your pen drive “drive letter”