What do you mean by the term "blank screen"? Is the screen black or it's blue? Does it show any errors?
You have to specify what exactly do you observe. Can you hear the drive or the fan spinning? How did the problems start?
If you can hear the drive spinning up, but you are unable to see anything on the screen, then the problem might by hiding in the video chip of the motherboard known as North Bridge, which is responsible for displaying video signal.
If you are unable to start the laptop and there's nothing making any noise there, then problably the hard drive or the power supply have failed.