Help my cat pressed something and now look

Hello,
Okay this just happened like 10 minutes ago. While i was exploring the internet my cat jumped up my bed. Then he pressed my keyboard keys, as soon as that happened The screen takes the whole screen, now i can only seen the start button when i minimize the page i am on. Also the tools and everything that you usually see at the top of firefox(tools, home, edit, ect) aren't there. I guess my cat pressed something to make the screen larger and i don't know how to fix this. If you need a picture of my problem just post.