Hp screen blank

Hello,
My laptop screen is blank and I can't see anything. I know it loads because I can hear it and the screen where it has f1-f12 at the bottom shows up and I can see it, however, when it's supposed to transitions to the sign in screen it, goes blank and stays that way. I can go into the programs for f1, f9 and f11, but it won't transition into the sign in screen. Can someone tell me the problem please? I tried taking the battery out and holding the on button down for 20 seconds, but when I do that it ends up turning back off at about 5 seconds.