Well, if you bought it recently, Walmart will usually allow for an exchange. I can't remember how many days though. They will not give money back, but they will do that. I know a few people who have made such exchanges.
Now if it won't come one, are you sure that the battery isn't completely dead? That is often the case, someone lets it get fully dead and then it has trouble actually charging. I would check this. And if needed replace the battery. They can be defective.
Lastly, I would suggest, if you can't exchange it and the battery isn't the problem, then a "Hard Reset" May be needed. However I would really save that as a last resort, as it wipes your data.