I was playing some games and when i was done doing that i turned off my pc,
but when i wanted to turn my pc back on it showed me a black screen and it doesnt turnoff either.
all the fans spin and all the cables are plugged in on the right spots including the cpu power cable.
I've had this problem before. Try clearing your motherboards CMOS to reset the motherboard. To do this their should be two jumpers labelled CLEAR CMOS on the motherboard. You need to take the jumpers off for 20 second then put them on the other pins next to them for 30 seconds and then put them on the original pins after waiting 20 seconds. I would look in your motherboard manual on exactly how to do this with your specific motherboard.