For some reason my computer screen has decided to go ‘all funny’

My wife could not see the START button on the bottom left of the screen.

I tried going on to the OSD settings on the monitor. When I clicked on H Position, then clicking on + - I managed to move the screen left and right. So now I have a choice, either see the Start button on the bottom left, and no icons or clock on the bottom right, or vice versa.

I tried going on to the H-SIZE button on the monitor, but nothing happens.

Any suggestions please

Even if I try to make the icons small, by altering the Desktop settings, via the resolution settings, there is no difference.

Any advice please would be appreciated

I have W XP

Many thanks !