I work in a nice clothing store and their policy is that after 90 days, all you get back is the lowest price an item sold for. So even if it cost $100, you may only get 2.98, as they keep reducing prices after almost all stores are sold out of the item just for cases like this. And I cant imagine any circumstance under which our manager would accept a return after 6 years, tags or no tags!

I have a better suggestion - donate it to the Salvation Army or Goodwill, get a receipt, (they don't care how much you claim) and you can take the full amount against your taxes as a donation to charity.