Question about trading in a video game?

So for my birthday, my friend bought me "Dance Central" for the Kinect on Xbox 360. I already owned the game and wanted to return it at Walmart where she bought it. Unfortunately, she lost the receipt and I couldn't trade it in for store credit because it was over $50. I don't know what to do with it now. It's still in its original wrapping. Can I trade it in to a store such as Best Buy or GameStop for store credit even if it's from Walmart, or what? Any suggestions?