This junk just happened to me, oddly & luckily this advice from an above poster did the trick!
I hope I NEVER have this problem again.
1.turn off both the gamepad and console
2.unplug console
3.hold the power button on the console for 10 secs.
4.plug the console back in
5.turn the system on using the gamepad, at first it will say the gamepad is not connected then shortly after it will register the device.