First state what type of monitor you have (is a flat panel, or a CRT - i.e. the ones that look more or less like a TV).
This problem is most likely to be fixed by adjusting the monitor through its configuration interface. Not knowing your monitor, I can't say precisely how you can access it, but there should be a number of buttons on the monitor itself. When you find the buttons, press them.
Two possibilities:
1. Your monitor has a series of dials which allow you to adjust things like positioning, contrast, etc. (This is unlikely as it is found on very old monitors, but if so play around with them until you manage to get it back to normal)
2. Your monitor will have a built in configuration GUI with a number of options for you to adjust.
- The first thing you should do if this is the case is to find the option for stretching the image onscreen vertically as well as the vertical positioning. Stretch the image so that it is of greater size, then move it to the center of the screen, repeat as needed.
- If you have a CRT monitor, and the menu has an option for "degaussing" you should give it a try, as it could solve all of your problems in one easy step.
That's really all I can say without any more information.
Edit: I missed where you said that no options do anything. Degaussing may still help if you didn't try it though, or possibly adjusting the refresh rate.
