I have encountered an issue that has caused me to loose all WiFi and Bluetooth functionality. The WiFi\Bluetooth device does not even show in the device manager unless show hidden devices is enabled.
The first time this occurred was Feb 2015. In order to regain functionality, I just ended up re-installing the drivers which seemed to work for awhile. (I ended up making a restore point as a marker to let me know at what point the Wireless and Bluetooth were working again)
The second occurrence was in March 2015 and re-installing the drivers did not allow me to regain normal functionality so I attempted a system restore...and that did not work either
If I try to update the drivers to the most current version (17.1.1440.2) I am still left without a working WiFi or Bluetooth device.
My hardware is the following:
Dell XPS 15 9530
Windows 8.1 Pro x64
Intel Core i7-4702HQ
16 GB RAM