To reverse this you will have to select My Computer on the desktop, then select Tools and locate the Folder Options section, then select the View tab and look under the Hidden Files section and select the Show Hidden Files and Folders.

There are programs you can download such as Microsoft Private Folder 1.0, but these are not used to protect your computer from hackers, they are just for protecting specific files with a password from other people that use your computer such as family and friends.  In order to use this program you will need to download it first of course.  Along with other hardware and software, which makes this an un-attractive approach to protect your files, I would suggest just hiding them. 

The best way to password protect your files is to use Winrar or Winzip, because with these all you have to do is archive the file and you can password protect the archive and place the file or folder in the archive area.  This is the easiest and only completely free method of doing this that I know of, all others require Microsoft Office or other software and hardware so I suggest this method. 

I’m sure there other programs you can download to do this but why would you when it is as simple has that, besides the fact that those programs will probably cost a little chunk of change.