hello people first of all this is my first thread for a whole month i was gone

now for the problem my laptop is an acer as the laptop is workin the right side of the screen isnt workin at all , it is completly black and i want a way to minimize the screen size how can i do that if i don't have the screen buttons ???

Have you checked that one of the backlight bulbs hasn't blown or has stopped working. Try to run it onto an external monitor, just to check that you can see the whole screen, then we can rule out any problem with the actual computer and limit it down to the VDU on the laptop

yes i have tried it with an external monitor and it worked

Well then, it looks like your inbuilt monitor is either broken or the backlight has failed. Have you dropped it recently or has it received a heavy blow or the like?
Also open up the laptop and have a check that the backlight is on one piece and hasn't broken/blown/dirt in the way.