I was helping a colleague with an HP laptop running Windows 8 today that lost its wireless capabilities.
What did not work:
The built-in HP Network tool could not fix it by disabling and re-enabling the wireless card and there was no way to search for wireless networks through the notification bar or the networking control panel. On the Windows 8 “charm bar” (press Windows Key + C) it said “WiFi (Off)”.
What did work:
Open the “Device Manager” and find the Networking Devices. Double-click on the Wifi card. Under the Advanced tab, find the list item for “Radio” and make sure that it is enabled.
I just found it interesting that the WiFi radio could be disabled but the only way to turn it back on is to dig through about three levels of control panels. Anyways, I hope this helps someone.