Legal Question in Consumer Law in Illinois

There is no "general" law such as you would like there to be. There are laws regarding credit purchases, and certain in home-sales. But as far as typical store retail sales, it is usually a question of "store policy" if they will accept any returns, and if they do that should be posted. What you might try, however, is whether they will issue a store credit, meaning you return the item but they keep your money that you can use to purchase something else that you do want and/or need in the future.