So, I ran the terminal command to show hidden files and folder. I then restarted finder to expose those files. When I was done, I entered the terminal command to hide hidden files and folders. Typed in "killall Finder," but then nothing happened. My hard disk disappeared from my desktop and the light below the finder turned off. Anyone ever have this happen to them? I didn't know what to do so I just ended up restarting my iMac.