If you bought a used car and was told it was fine but later you found out it had issues can you get your money back?

Only if the car was sold with a warranty which made this provision.

Most used cars are sold as-is, and so the rule is "buyer beware." If the car was purchased from a reputable dealership, a friendly call of inquiry (be nice) may convince them to repair the car or otherwise compensate you in the spirit of goodwill and customer satisfaction. Some dealerships will, most wont, but either way the worst they can do is say no.