Screen is white when I turn my laptop on?

About a year ago I got an Inspiron 1545 as a graduation present. A few months after I got it I started seeing a white line across the top and the display wasn't as "smooth" as normal. I ignored it, not thinking it'd get worse. However, this morning I turned it on and the screen was immediately white. It got stuck on "loading windows" or whatever, so I turned it off and restarted it. It was fine. I turned it on a few minutes ago and the screen was white. I heard the "windows logon" sound, pushed against the screen (which is what I do to get it "smooth" again) and it showed the screen (unsmooth) and froze. But after a few seconds it was back to normal. Any idea what's going on and how much it would cost to fix? I need it for my first year of college in August. :(