I was in the similar situation and I had almost done the hard reset. But luckily I found below solution.
1. You have to unlock your phone any how.
2. When lock screen appears, double tap on the screen. It will ask you for password.
3. For entering password, press the number first and then double tap on it to input.
4. This should unlock your phone.
5. Now open the Cortana by double tapping search button.
6. Now speak "Open Ease of Access".
7. This should open your Ease of Access settings.
8. There you will find the option to disable narrator. Double click and you are done.
You have been saved from hard resetting the phone.
And never use the narrator feature on windows phone if volume up button is not working.
06-06-2017 11:37 PM