If you are faced with the situation whereby your laptop powers up but the screen does not turn on (known as the black screen of death), then there is a good chance that one of your memory modules is corrupted. Try taking each of the memory modules out in turn to see which one is corrupted. Once, you have identified the corrupted memory module, take it out and leave it out. Now your screen should switch on. Should you require the extra memory, you can buy it from somewhere like Maplin or PC World.
Another problem that can add to the black screen of death situation is a corrupted hard drive. You can purchase a data cable that is a SATA I/SATAII & IDE to USB2.0 Adapter. This allows you to take a hard drive out of a problematic laptop and format it using a number of different file formats from a different computer. Once the hard drive has be formated, you can then place the hard drive back into the laptop and insert an operating system install disk to reinstall the operating system.