Sometimes updating the drivers will allow you to get higher resolutions from the graphics card. Check with the card manufacturer, or if the card is built in to the computer, contact the computer manufacturer.

Sometimes, it may be that the Operating System is not detecting the monitor's maximum size correctly. This might be corrected by installing drivers for the monitor itself. You should be able to get these drivers from the monitor manufacturer.

__________________
The best way to learn anything, is to question everything.