one day I updated my archlinux through pacman -Syy. when I reboot then it get black, and I try to fix it through close a series of command in .xinitrc when I closed this command "xrandr -S 1920x1200" then the xorg was able to work just the word too small I try to change other resolution but all could not work Two day's latter I backed up my date in my laptop and reinstall archlinux xorg and dwm, the xorg couldn't work also. thank's for your help
change my resolution to 1920x1200