Well, I would like to say you the solution. Follow the below simple steps :-
1) First check out that navigation button is enabled or not. If disabled, turn off the button to enable.
2) Your 2nd step is go to phone settings.
3) Search additional settings or scroll down the screen to find the option.
4) In additional settings you’ll get a feature called quick ball. Tap there!
5) Turn on the quick ball and come back. You’ll see a circle beside your screen. So, click there and you’ll see back button, navigation & all.
That’s all, hope these simple steps help you
THANKS
Anjis_techlite.info 