Laptop displays normally when turned on then displays nothing later (black screen)

[Kradnostrad]

When I turn on my laptop, the screen displays normally. But a little later (just seconds later) the screen blacks out but the laptop is still running, the display just went off. What is the problem of my laptop?
Please help me, please.

My laptop model is HP Dm4

 

[Sp00kie]

Do you have an external monitor connected? Check the manual to see if there is a keyboard function combination to select display output device. Maybe some program you installed is switching output devices.

 

[Prostar Computer]

Do you have an external monitor connected? Check the manual to see if there is a keyboard function combination to select display output device. Maybe some program you installed is switching output devices.

Solid advice. If you don't have an external monitor in use at the moment, can you connect one? Then you'll have a picture to troubleshoot. If you don't have a hotkey on the keyboard for switching the primary display, you can try it through Windows' screen settings (if you can get a picture on an external monitor, that is).