Check if the files are not in hidden mode.
Click on "Start" -->Run --> Type cmd and press Enter.
Here I assume your pendrive drive letter as G:
Enter this command.
attrib -h -r -s /s /d g:\*.* --> Press Enter
You can copy the above command --> Right-click in the Command Prompt and
Note : Replace the letter g with your pen drive letter.
Now check your pen drive for the files.