i lost my ipod touch at school

so the last day of school was last week (june 26) and i lost my ipod on june 18. on june 16 i brought it to school for a presentation. we had an indoor recess that day because it was raining so after recess, i was in a rush to get to music class because i have been late several times already so i put my ipod on my friends desk. after music, it was gone. i checked my locker and it wasnt in there. the lock on my locker is messed up because if you pull really hard on it it opens without entering the combination, so after school my friends told me that my locker was wide open. the next morning i found my ipod in my locker. i put it in my backpack and brought it home. i brught it back to school the next day (june 18) and again after lunch recess i was in a rush to get to music class so i put it in my friend's locker. It isn't actually her locker, it is an extra locker that nobody uses so her and her other friend put their stuff in it and so do i. I also keep my alto saxophone in that locker so i didn't think it would be a big deal to leave my i pod there. I also put my earbuds in there. After music i looked in the locker and only my earbuds were in it. A few days later i told the office and i watched the security camera and literally NO ONE went to that locker so i am really confused. I looked through the entire locker several times to make sure it hadn't fallen or anything. It was dead when i put it in so i can't use find my iPhone and i had tried using it several times and each time it said it was offline so i dont think anyone has stolen it. and im 99% sure that my friend didn't take it so i don't know. Can i track it with the serial number or something? it was only 8 gigabytes and it was really cheap but i still want it back because all my pictures from travelling are in it