I don't mean to discourage you from writing (I'm a writer), but wizards has no interest in publishing fan fiction or in publishing outside of their marketed campaigns (Eberron, FR, Dark Sun).

If you're passionate about the work, go back and change the names and some of the details and then just hit up every editor/publisher you can get your hands on. You're much better off doing this independently than begging at the feet of Wizards ... after the debacle of 4E, Essentials, and D&D Next, they have no idea what they're doing.