Screens Gone Wide

Hi Everyone,

Hope someone can help. My son did something on my keyboard and now all
screens have stretched wider than the actual screen itself! I've had a look
at screen resolutions but this doesn't seem to solve the problem. To give
you an idea I can't see the Start button or the icons on the bottom right of
the screen.
Also all windows have a slightly convex look to them. This is a system
problem as I have reset the default settings on my monitor.

Thanks in advance.