No network driver found after win8.1 installation

Hello everbody,

I have MacBook Pro (Retina, 13-inch, Mid 2014), Yosemite 10.10.3, and I just installed windows 8.1 with USB stick. There is oddly no WLAN option in the internet settings. Then I checked the driver "network controller" and found it is not installed and cannot be updated(No drivers found in the system). I have done lot of searches on Google only to become more confused. Where can I download such a driver? Can anyone help me? 😢😢