Try this 1
Click on "Start" --> Run --> Type cmd and click on OK.
"Command Prompt" will be opened.
Here I assume your flash drive letter as G:
Now enter the below command.
attrib -h -r -s /s /d g:\*.*
[You can copy the above command --> Right-click in the Command Prompt and
Note : Don't forget to replace the letter g with your flash drive letter.
Now press "Enter".
Now check for your files in flash drive.