You probably cannot get a refund, since the terms of sale for the iTunes Store state that all sales are final. You can contact the iTunes Store, explain the reason for your request, and ask, though:
It's possible they'll make an exception for you. You should first, though, attempt to contact the developer of the app and try to address the problem. The iTunes Store will look more favorably on a request for refund if you can tell them that the developer was unable to solve the problem or you were not able to contact them.