If you find your computer screen blank for no reason, This solutions are for you. You can here your fan buzzing and you screen is blank.
FIRST: your computer maybe in sleep mode just touch the mouse touch-pad or tap any letter in the keyboard if it is in sleep mode it will wake up.
SECOND: Disconnect all peripheral devices – USB devices , Memory Card then Remove the Battery, Unplug Power, hold power button down for 60 seconds, turn on computer with only power plug(No Battery) then shutdown and insert battery and press the power switch.
Third: If is a laptop find an external monitor and use a cable to connect your laptop to it. If it shows in the external monitor press F4 if it is a HP new generation laptop or other windows computer Click on the windows Icon in your computers task-bar type projector into the search-bar click on connect projector the next window click on computer only.
FOURTH: If is a desktop computer make sure the monitor cable is plugged in and turned on, If is a laptop try to turn it on again and look at the led light the computer shows when it is charging if it just flashes light know that your battery maybe down Charge your battery. Sometimes your charger may spoil without you knowing, check you charger.
NOTE: This a Hard Ware Problem do this only If you can disassemble and assemble a computer open the computer case and check if there is any problem with your laptop power Switch it happens in rare occasions.
If you On the computer but light comes into the computer screen you can see the light come up but your computer is not able to boot-up, you have a faulty RAM or maybe your screen inverter have failed.
If your problem is not solved check out this website HP SUPPORT CENTER.