You need to know your graphics device.

It is most likely either NVIDIA or ATI or INTEL (embedded).

Look in your Control Panel > Add or Remove programs and see if you have any of the above listed as installed.

If you do then remove the graphics driver and get a new one from either NVIDIA or ATI or if it happens to be INTEL go to your computer manufacturers driver page.

Drivers - Download NVIDIA Drivers

Graphics Drivers & Software

Or your computer manufacturers web site > Support > Drivers > Video or Graphics.