xrandr to change display resolution setting

xrandr --newmode 1600x1200 229.5 1600 1664 1856 2160 1200 1201 1204 1250 +hsync +vsync
xrandr --addmode default 1600x1200
xrandr --output default --mode 1600x1200

replace 'default' with proper output (xrandr -command should show it. It can be VGA, VGA1, VGA2, LVDS etc...)

if above method fails, you may need to add Virtual 2048 2048 to your xorg.conf. example:

Section "Screen"
Subsection "Display"
Virtual 2048 2048
EndSubsection
EndSection

then restart your x and try xrandr commands again.