What do you mean by "perfectly started"? You can hear the drive or fan spinnig, right? If you do, then the problem that you encounter might be due to the failure of the video chip. Sometimes, after much of a use and less cooling the so called North Bridge, which is responsible for video signal transmission get unsolders, the thermic paste is gone, therefore the screen doesn't show anything. If you possess knowledge of notebooks' hardware you can change the paste yourself by opening the laptop and check if the chipset that is next to the processor has got unsoldered or you can bring your laptop to a technician to get it soldered again.