HELP! I AM IN TROUBLE! 10 POINTS?

so last friday I was at my Locker ( im in 8th grade now) adn this guy I knew from elementary school asked if he could Borrow my History Book for class. Over course being the tired( i don't think when im tired i just do), nice person I am I agreed and he said hed give it back to me later that day. i couldn't find him or my book for the rest of the day. ( we have lots of people at our school so yeah) then i find him Monday and say hey can you give me my book back? and he said he GAVE IT BACK TO ME and LAYED IT DOWN IN FRONT OF MY LOCKER IN THE HALLWAY( WHERE PEOPLE ALWAYS WALK THROUGH) and didnt have time to argue and I saw no history book anywhere near friday or monday. So idk what to do he had to be lying or he just has no damn common sense( why would you throw SOMEONE ELSES BOOK WHO WAS NICE ENOUGH TO LEND YOU IN THE FIRST PLACE THAT IS NOT YOUR ON THE HALLWAY FLOOR WHERE PEOPLE WALK) Then i figured it might be in the lost in found if HE IS TELLING THE TRUTH I go look for it its not there. No im really pissed don't know what to do I cant just break in his locker to see if its there. ( we have 14 days of school btw) and dont know where to go for someone to help me I owe 50- 70 dollars if someone does not turn it in at the end of the year AND THE FUC$!NG BOOK WAS PROBABLY PUBLISHED IN 1992 I AINT PAYING THAT ! i know it was my stupid fault for lending it out in the first place. But Im not sure if my first hour teacher will help me he isnt always that nice and will PROBABLY be like well, your fault im not helping you and my pricipal this year is a Jerk so he isnt gonna listen. ughh why do I have to me a nice person. ( and just a reminder I dont get on my first hour teachers nerves I always behave in class and i never get sent to the office for bad reasons) and all of our teachers and prinicpals ALWAYS SAY STUFF LIKE " IF YOU NEED HELP OR HAVE A PROBLEM OF ANY KIND YOU CAN COME TO ME" and its not like a can just beat him up to give it back to me because 1. Beating him wont really get him anywhere,and im a girl and I will get arrested! and I cant really confront the guy some more because he probably will just keep lying he has to have it i know he just has to. and if the Janitor or a teacher/ student found it somehere the would not just throw it out they would throw it in the lost in found, What do I do? AND I need my book to do my work!