Laptop screen is black but when using a projector it work. What the problem? Because I have changed the screen but still same

[Aliff_]

Please help me

 

[The Paladin]

make and model of laptop please, and did you change the wiring that leads the screen to the motherboard ?

 

[BAM-GUV Bambi]

Sounds like the projector has taken the resolution beyond what the monitors can cope with.
Try hooking the projector back up, changing the display to something you know the monitors can cope with (1280x1024) and then swap back to the monitors/laptop display.