It is possible the problem may be software related. If you can try a different monitor and see the same problem, then software is most likely the problem. Or you can just reinstall or update the drivers.
You can re-install the video card driver, or check for a new driver at the card manufacturers Website. If your video card came with your computer, the computer makers site may have have a new video card.
You can also reset your monitor in the Display Properties window, Settings tab, Advanced button.
Right click on any unused portion of the Desktop and select "Properties" to open the Display Properties window.
You can determine what video card you have by right clicking on "My Computer", then selecting "properties". Select the "Device Manager" tab and click the + sign next to "Display Adapter". Then select the device and click the the "properties" button.
If nothing helps, then I would conclude a new monitor is going to be required.
Here are some links to other monitor Questions and Answers:
Monitor HelpMore monitor help needed.Perhaps something in one of this posts may help.
Good luck with this!

I hope yours is a great day!