I bought a used car one day ago and paid 1000 down payment. Can I change my mind within the next two days, return the car and get my down payment back.

What reason do you have for returning the car? Is it a lemon? Is it not what the dealer promised you?

This was actually discussed in an earlier question regarding a rental property:
https://www.askmehelpdesk.com/real-estate-law/3-day-right-recision-deposit-rental-property-269187.html

Based on what others have said there, I don't believe you can return the vehicle.