Boots up but displays white screen only

I was browsing when all of a sudden my screen turned white. I powered down and turned it on again, and all that comes up is a white screen. No apple logo or spinning wheel. However, the chime does sound. My attempt to blindly log on was successful, and after randomly pressing the trackpad, was able to play an audio file. So, the computer boots and everything, just nothing shows up on the display. I have tried resetting the PRAM, SMC, safe mode, booting from DVD--no luck. Unfortunately, I am 6 months past warranty (of course!) so am trying to figure this out without having to call apple. Can anyone help me please? I am a student, and with finals coming up, desperately need my files and laptop. Thanks!!