How can I get the terrible smell out of the closet?

So I recently moved into a new apartment and the broom closet just off the dining room smells awful. I keep a large garbage can in there and I can only ume that the people who lived there before me waited for everything to rot before bringing it to the dumpster outside. The smell is so terrible that I urge when I open the closet door. I have tired air fresheners and so far nothing has worked...Please Help!!