My computer is an acer Windows 7. My computer engine I can here, but I have a black screen. How can I get help with this problem.

Have you tried booting into safe-mode?
If you get the screen back there, you can re-install/update your graphics drivers.

i would test the screen on another computer first if possible to know if it's the screen or the video cards

Could be that you're having a graphics processor overheating problem, or your cable is not connected properly. It could also be that the display is not powered on!
It doesn't matter how good we get at working on computers, silly stuff still happens all the time!

Sooo very true. (Is the power cable plugged in?)