Then it's likely a damaged screen. If you are lucky you can use the laptop until you get it replaced. There are a lot of YouTube videos on replacing LCD screens so I won't duplicate any advice or prices for that here.
But some ask if you can repair the LCD screen. No. You replace them.
HELP: DX Fast answers please! There's this huge black dot and several lines and weird stuff on my computer's screen, no cracks or anything, I just came home from school today (maybe I could have sat on it while getting out of bed, but I don't think so...) and turned it on, and there the monstrosity was!!! I can't buy a new one, have no gurantee (bought it used from a friend,) What do I do? DX What is this problem and how do I solve it?