What happens if the power button is missing from my iPhone?

I accidentally broke it. I probably pressed too hard and it fell off. It was so quiet, and I didn't notice until I was trying to screenshot something but it didn't work because the power button is MISSING/GONE. I'm shocked right now as I have NO idea what to do.

How did a picture message get sent from the wrong number?

My dad sent me a picture message, we both have iPhones but are not using iMessage. When he sent the picture it came from a local number that was not his. When I responded to the text message, the number replied that I had the wrong number. I sent a screen shot of the pictures and they had no clue. It is not someone my dad or I know. I then told my dad about it and he resent the same pictures and they came under his name this time.

I'm wondering how this is even possible? How could the messages get sent under a different, but activated number who never sent or saw the pictures before?

Any ideas would be great!

Which IPhone is better out of IPhone XR or IPhone XS Max?

I originally bought an IPhone XS Max for Christmas until the screen stopped working on the day the first day it was opened and had to send it back to Tesco mobile. My brother was bugging me to get the IPhone XR as he thinks it's better and less glitchy. What do you think?
Does anyone of you lot out there own any of these phones and can you tell me if you have had any problems using the IPhone XS Max if you own one please?