Unhide Contents in Pen-drive

Press the Windows button:

Type: cmd.exe
You'll see: Command Prompt
Right click the 'Command Prompt' and select 'Runs as Administrator' from the options.
Select 'Yes' when prompted for permission.

Now, you'll get a command prompt window with prompt as:
C:\Windows\system32>

That shows that you have followed the correct procedure. Else, close the current command prompt window and re-execute the above procedure to get the correct prompt. This will give you the necessary permissions for modifying the permissions of the files in the pen-drive if necessary.

Now, note the drive letter of your inserted pen-drive. Lets say it is E: drive letter for my case. Use your pen-drive drive letter for your case.

So, use your drive-letter as below:
C:\Windows\system32>E:

And I get:
E:\>

Now, execute the following command:
E:\>ATTRIB -S -H  *  /S /D

When complete, check your pen-drive if you see the hidden files now unhidden.

Thank You.