Can I win a case to get my money back for the purchase of a car that stop working less then 3 weeks of me purchasing It

Maybe, but there is no way to know without knowing a lot more about what happened in the sales process and what your sales papers say. You should try to work it out with the seller or dealer if you can. If you can't then you should call your local bar association and ask for a referral to a car sales fraud or consumer law attorney near you so you can sit down and go over all this and find out for sure what your rights are. If you bought it from a private person, the only requirement on the seller is to deliver a valid title to the vehicle and not to lie to you about anything during the sale. Car dealers have a lot more legal obligations and, frankly, they almost always violate one law or another in selling cars to consumers, but you need to talk to someone who knows car sales fraud laws to explain for sure what your rights are.