i increase my screen resolution from 1399*780 to 1980*1280 and then my desktop not working give me signal not responding with black screen then i restart computer but it doesn't work how can i start desktop. it doesn't show any thing.
Did you press enter when the screen was blank (when you change resolution it has a 15 second countdown and if you don't press anything it will revert).
It seems you will need to boot into safe mode and reinstall the graphics driver (it's a good excuse to look for an updated driver on Intels / AMDs / NVIDIAs website).