You need to go to your mobo's website and download the LAN driver. If you fill in your system specs this will help us locate the needed drivers. For now I just need the make and model of PC - exacat make and model.
Note: when reinstalling windows, it's recommended that you download and save all current drivers and mobo software to a flash drive. Once the reinstall is completed all you have to do is load all your drivers from flash drive.