I think I "broke" the OS 11 upgrade for my iPhone. How do I reinstall?

I upgraded my iPhone 7 to OS 11, and it worked fine for a couple of weeks, but one day I was laughing about the new "enthusiastic Siri" to some friends, and ever since, Siri has downgraded herself to such a monotone, robotic voice it's like an anti-Turing test. Also, my photos don't always orient properly. Can I reinstall? Will that fix it? And if so, how do I do that?