I NEED HELP IMMEDIANTLY!?

[Alexia]

Okay. I'm only 13. On Thursday, I lost my Iphone 4. As I was driving to school the next morning, I found out someone hacked my instagram. They changed the username to "slutgirl123456" and posted a picture of me and my 2 best guy friends and the hashtags said: #sexy, #cantwaittilltonite, #loveyousexyguys#lightsout. (Note: My instagram was already logged on my phone, but my phone has a password on it.) So, I figured that the person who hacked my instagram has my phone. I reported this to the principal as soon as I got to school. She checked everyone's things. 30 minutes later after we didn't find anything, she told me to get to class and she'll check things out later. As I opened my locker, there was my phone. It was cracked, and had 0 battery life. I reported this to the principal also. Much later, we narrowed it down to 5 people in my school. After school, I charged my phone. But, my password was changed. Is there a way to get past this? I have iOS 7.1. Plus, I did not tell my parents yet because ALOT of other things have been going on and my dad is very stressed. Please, please help me.