I Lost My Phone And I Don’t Know What To Do!?

I was walking home from the bus stop after the first week of school last week and I started dragging my backpack that wouldn’t close (a shoulder bag) on the ground as I passed my neighbor’s house. (First house in the neighborhood on the left) Two boys were walking behind me. One I can trust, and one that I have known since I was two. (We used to fight a lot and he hits a lot of people) They were the brothers of two of my friends. (Not from the same family of course) When I heard them laughing, the innocent one yelled that I dropped something and I turned around and saw that a fruit cup fell out of my backpack and they started tossing it around when I said they could keep it. Of course, the violent one smashed it against the sidewalk when he thrust it in the air. I just turned around and kept walking. After that, I never saw my phone again. It had no phone number (It’s new), no sim/memory card, and no internet access YET. It had a purple cover and it was signed by a bass player from my favorite band. I never took it out during school and I put it in the front pocket of my backpack. (No zipper or button to close it) When I started looking for it, I noticed a hole where my phone had been when I started dragging it. My mom is talking to the violent guy’s mother right now asking if he had found my phone but of course, they’re a bit of a cheap family and his sister (my “friend” that I don’t really like) really wanted a phone because she’s the only girl in our grade that doesn’t have a phone. Nobody knows my phone is useless so they would definitely take it. It was a Nokia 5230. Very expensive, and I got it from my dad even though I asked for a new phone for my birthday. (In a month.) (I got the phone a few months ago) What should I do?!