Follow these simple steps:
1) Click on the USB Drive and make sure the files/folders are not hidden by checking the Folder Option.
2) Go to Start > Run or Press Window + R and type cmd and press enter.
3) Command prompt will be appeared on your screen.
4) You will see the C:> prompt.. Start typing attrib -h -r -s /s /d g:\*.* in command prompt. Don’t forget to replace the letter (g) with your pen drive letter.
6) Press Enter and You are Done!!
7) Now go to Windows Explorer and now your files and folders are visible.