Hey there Smarcav,
So, now when you boot your laptop, after the initial welcome screen, the display becomes black, is that correct? Can you see the cursor blinking or it's completely black? If you can, the first that comes up into my mind is to restore the system through a repair CD if you have one.
The second thing is to restart your computer, go after pressing the appropriate F key to navigate to the Windows menu. From there you should have access to restore your OS. Open the Command Prompt in safe mode and run the command:
sfc / scannow
Then press Enter and wait for your OS to be repaired. If you cannot access this menu while you reboot, enter the BIOS settings. There, navigate to the storage menu to verify that your hard drive is as a first boot priority. If not, set it!
If there's nothigng to show up I suggest that you connect the laptop to an external monitor to see will there be any video signal going out from the laptop. If it does go out, then there's a need for LCD inverter replacement. If there's nothing showing either on external monitor nor display, but the fans are still working, the problem that you have may be due to the failure of the video chip. Sometimes, after much of a use and less cooling the graphics processor which is responsible for video signal transmission get unsolders, the thermic paste goes away and it gets unsoldered, 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.
Once you have done this please, come over here to tell me what happened. Cheers.