Affiliate Marketing Secrets

Some girl stole my iPod. There seems to be NO evidence pointing to her. However, on her email and Facebook account (messages), there is TONS.
Okay, so here is the back ground information:
-I am underage, 15.
-I talked to the school cops, but nothing yet.
-I have the passwords to both this girl’s Facebook profile and email.
-There was not much proof, but there is TONS now.
-I realize it is invasion of privacy.
-There are so many messages proving her guilty (on Facebook).
-On her email, it says she has used my iPod, which she stole, so many times.
-She is gang-affiliated.
I need help. I want it back. We know who it took it and want it back. They told me if she was found guilty I could press charges, but could she also press charges on me for looking through her stuff?
I’m scared and confused.
How much trouble would I get in if I took pictures of the evidence and presented to a police officer?
What would I say?
A school English teacher said that it was evidence/proof and that I would not get in trouble myself.
Although, some other kid told me I could face 1-5 years in Juvenile Hall, then prison.
Any help with the legal stuff?