I suggest you try the "hard reboot" process:
1. remove the battery and unplug the wall cord
2. hold down the power button for 30 seconds
3. insert the battery and plug the cord back in
4. try to start the laptop again
This will sometimes allow the laptop to reboot.
If this doesn't work then you will need to determine if the laptop has a bad screen or a problem with the motherboard/CPU. That will probably require a qualified computer tech with hands on access.
Does the Windows start sound play? If so, that would point you to a failed screen.