Comment 5 for bug 823615

Also check the AT keyboard device with input-events to see if the wlan event appears. It doesn't look like there's any WMI hotkey event for your wlan hotkey. I assume your other hotkeys are working and generating events on the hotkey input device? It may just be that your machine doesn't generate a key event for the wlan key, as odd as that would be.

I can generate something that looks the same just by running 'rfkill block all' then 'rfkill unblock all'. My device isn't dead though -- I can get it back by deselecting and reselecting "Enable Wireless" from the applet, for instance. Give that a try, and if your experience matches mine then I think this is a network manager bug.