Hello I am from Iran,I have one question I lend my book to my teacher but he does not back them?

I would simply ask for the books back, and explain that you lent them to him. Do it respectfully, like pulling him aside and away from everyone. Just say, your teachers name, I really would like to get the books I lent you back. I hope you enjoyed them as much as I do, but I would like to read them again. Thank you for understanding. Your teacher probablly just forgot about you lending them to him and so a simple reminder like the one above will remind him to give them back.