Everything on my PC is stretched to wide!!! I dont know what option or setting was changed......?

What happened was my two year old got ahold of my keyboard and went to town banging it with his tiny little fists. I came home from work and my browser displays everything too wide and/or big. Pictures on web pages are of super low quality and stretched way too much.My start menu is the size of the entire screen. I tried increasing and decreasing screen ssize, resized browser , adjusted screen resolution, just about everything i could think of including the DPI. I'm seriously lost. what could my son have done by just banging random keys?