My school says i owe a textbook and won't give me my metrocard?

Your teacher should have a master list of all the students in her cles, their names and the number of the book checked out recorded next to each name. When you returned the book, your name should have been checked off the list. Ask to see the master list, to check if your name is checked off and this a simple error. If you want help from your chem. teacher, I would change your attitude.