Is it illegal for someone to falsely accuse you of theft, if so can you sue if you are being accused?

I am a teen looking for help. I have been accused by a teacher of stealing school property. she has told me that "If i don't get the camera back, I'm going to get the police and principle involved." This is apposing a threat to me. Because I did not commit this crime i was looking for some legal help on the situation. Anything will help! Thank You.