are you turning on wifi or blue tooth? those are 2 different things...
If it's the bluetooth, try Fn+F6
If it's the wireless, there's a special key on top of keyboard "capacitive touch keys" there's an icon with antenna that signifies wifi, which switches wifi on/off
if those keys aren't working try Fn+F1 (this says it only turns the LED lighting for those keys on/off but it might be the functionality too)