at first,as mailpup said- check,do you have drivers. you can go like this: Start->run->dxdiag->Display (it will show what driver currently is installed(main driver version,date and all about your graphic card.). If you have the driver,download the new,uninstall old version,reboot your pc,and install the new driver again. Depending on your graphic card,maybe you have the VGA and HDMI connector at the back of your graphic card. If you'r using VGA connector,try to use HDMI. It will require a reducer(which should have come with your graphic card). It would be great,if you would told,what graphic card you have,and what OS... you also did't said- your graphic card is integrated,or on AGP/PCI-E slot?