To remove the problem this is what you need to do.
1. Go to Folder Options -> View tab
2. Make sure that your Show Hidden files and folders option is enabled.
3. Uncheck the option that reads “Hide protected operating system files (recommended)”
Now when you see your pen drive, you will find that your data is present there but in hidden form. There are 2 ways to unhide the data, either right click and uncheck the Hidden box or type in the following command in the command prompt
attrib filename –h –r –s
where filename is the complete location of the file.
Share your comments if it solved your problem.
Thanks & Regards