You need to read the return policy closely… although it gives you 14 days to return it, and then even if the item wasn't as advertised or described or didn't fit in the case of clothing. Additionally, don't be surprised if you have to pay for return shipping.
As marje said, re-read Ebay's policy and follow the directions, especially as regards contact with the seller. Ebay usually leans towards protecting the buyer, but only within the established policies and procedures...