Just in case your Windows has being infected by some viruses or worms which caused some folders to be hidden, you can try this step :
- Open command-line. You can use either Start -> Run or Windows + R then type cmd
- Type this command :
attrib -s -h /s /d "h:*.*"
which “h:*.*” is the example path
This command would be act recursively to all files and sub-folders inside the defined path.