Your motherboard must have dual-lan. If you delete the connections & reboot, Windows will redetect and set them up, but no guarantees if it'll enable file & print sharing.
Right click on the nvidia one & go into properties and there should be an item called File and Printer Sharing for Microsoft Networks. If it's unchecked, check it. If it's not there, click install >> service (may have to go Have Disk then type in c:\windows\inf)