None of these worked for me, I have a lenovo without a numberlock key, on my keyboard, on the Esc key (top left) in small print (just like f1, f2 etc..) it says FnLk, which probably means Fn lock. To disable the Fn key from being lit/locked, hold down the Fn key and press the Esc key. That's the only thing that worked for me. this drove me crazy until I realized how to fix it! And I'm very computer-literate, these little windows issues always seem to pop up and you feel stupid when you find out how easy it is to fix lol
The Fn key is always on in the sense your "NUMBER LOCK" is truned off.
By mistake sometimes you press "Fn + Num lk" which disables your default key functions and enables numbers instead.
Just turn on the Number lock by pressing "Fn + Num lk" and you are good to go...!!