Problem with firefox, please help?

After deleting internet history last night, I got back on this morning only to realize my toolbar was gone as well. While attempting to search for an option on top of screen to try to fix it, I inadvertently clicked to "full screen" meaning I can't "X" off anymore. It seems the only way to get off of it is ctrl, alt, delete. How can I fix all this? It is firefox 4. Thanks for any help! :)