Can't view entire screen on external monitor

Ok let me break the scenario down i have a mac book pro, i work for marvel and i am currently editing pilots filmed for possible production. I have a deadline in two weeks and just like a genius i dropped my mac and the screen is destroyed. I had a bright idea to use an external monitor because i can't afford to fix my mac till i submit my project and receive my commission check so I NEED HELP. When i plug in the external and hit command f1 it shows me only the right side of my screen and i can not open preferences to resie the resolution because the apple and the window opens on the left side of the screen which i can not see nor can i move the mouse to guestimate where the window is to physically move it over. I am out of options and Apple won't help me unless i have 500 dollars.I know i'm apple savvy but i know for a fact some of you guys are actual experts please assist me so i can see my entire screen on my external.