I plugged in a dongle into my macbook in order to use a projector. Usually I plug in the dongle, the screen on my computer turns blue, the screen on my macbook looks zoomed in/resolution changed then whatever is on my computer screen is projected on the screen. Then I unplug the dongle and my computer screen goes back to normal. I have had problems using the dongle and screen before. Sometimes it takes awhile to connect and sometimes what is projected on the screen is an extension of my computer screen (NOT what is exactly on my computer screen). This time I had some more trouble getting the screen to connect to my computer and when I unplugged my dongle my screen is zoomed in/resolution is off. I tried plugging in and unplugging the dongle to get my macbook screen to go back to normal but it hasn't.

I tried using Command-Option-P-R before the gray screen when it starts and the desktop looked normal. When I reset Safari and restarted the computer my computer changed back and looks zoomed in again.

I also tried System Preferences --> Displays --> Display tab --> Resolutions and I could not click Displays because it is grayed out

I don't know if this is relevant but about 5 days before I had the zoomed in problem some of my files have disappeared.

How do I get my screen to look like it normally does?