Windows 7, 8, and Vista hide important files and folders from view to keep users from deleting or otherwise modifying files they shouldn’t, but a simple checkbox can change that behavior.
On Windows 8.x
You can use the Ribbon to get to the Options page:
On Windows 7 or Vista
To show hidden files, just click on the Organize button in any folder, and then select “Folder and Search Options” from the menu.
Showing Hidden Files and Folders
Click the View tab, and then you should select “Show hidden files and folders” in the list. If you are trying to get into the Windows directories, you might want to also remove the checkbox from “Hide protected operating system files” as well.
Once you are done, click OK.
Note: If you are missing this option entirely, you should follow this guide to restore the option.