You got a cat at home that can configure multi monitors on a computer?! Wow!
Well, try rebooting the computer, then before the "Starting windows" appears, press "F8" repeatedly until a menu appears. If it prompts you to select an operating system, press F8 one more time, that should bring up another menu. Use arrow keys to select "Enable low-resolution mode" and press enter. It should boot.
Note that everything should be very big on your screen now, but you should be able to reset the settings that way