How should I force this shopkeeper to return my money?

I live in a small town and there are only a few shops that sell computer games. These games are pirated and are sold for the price of original game. I bought assassin's creed brotherhood yesterday and out of the three DVDs, one was blank. The shopkeeper had said earlier that he does not give any guarrantee that the games will surely run. Will I be able to get my money back?