hey for starters i know nothing about computers. my dad just gave me his laptop cause he got a new one about a month ago. i clicked on a popup by accident and i think i downloaded a virous or something. it shut down and when i start it up it sits on the windows loading screen for hours. now i dont care about any of my dads files cause he backed them up on his new computer. my ? is how do i get rid of everything on it and start over??