He bought me a car now he wants it back

Is the car in your name or his?

Is he still paying for the car? If it's in his name, it's his car. If it's in your name, you can fight to keep it, but, if he's still making payments on it, and it's in your name, and he stops making payments, which I would do if I were him, then it's your credit that would be ruined.

How is it titled?

1. Who is he?
2. Why did he buy you a car.
3. What type of paper work did you sign or agree to
4. Is there a loan on the car, and if so, whose name is on the loan?
5. On the car title, whose name or names is on the title

Where is this at, laws can vary by location.

Why does he want it back?