Open your PC case by laying it on its side, separate the power and unscrewing the access door from the case. The door is attached with few Phillips screws on behind of the case. Unscrew the Ethernet card from the PC and pick it out. Put the card back in, if possible in a new open slot if you have one. Screw the card back in. Close the case and again start the PC. Windows must find the card and ask for drivers. Put in the drivers CD and browse to proper folder and select the Ethernet drivers. Permit Windows to over installing and starting and the controller must be reinstalled. If the controller is not working, go to Device Manager, under System in Control Panel, choose and delete the Ethernet Controller and try again.