So what exactly did you try before concluding that xrandr did not work? Did you try anything at all?
What happens if you run:
xrandr --newmode 1280x1024
xrandr --addmode 1280x1024
You may need to add
Then run:
xrandr --output LVDS --mode 1280x1024
Please read the tutorial on xrandr that I linked to, and try to use xrandr as per those examples in the tutorial.
when you reply, try to provide as much info as possible instead of just "It didn't solve the problem". I have never hard to use xrandr myself, so I am not sure what the expected outputs would be from using it.