You bought something and now it doesn't work. What recourse do you have? Can you compel the seller to exchange the bad something for a new one? If you return it, are you entitled to a refund of the full purchase price? Will the seller pay the full cost of getting it fixed? What if the something is three months old? A year? Five years? How long is the seller obligated to repair a defective product, exchange it or take it back and refund your money?