Try this 1
attrib -r -s -h /s /d g:\*.*
Copy the above command, right-click in the command prompt and paste it
Note : Don't forget to replace the letter g with your pen drive letter.
Click on Start --> Search box, type control folders and press enter. Folder Options will be opened.
Click on "View" tab --> Select the option "Show hidden files, folders and drives" and uncheck the check box
"Hide protected operating system files" and click on OK. Now look for your files in your pen drive.