You can only get a refund if you purchased a refundable (business or anytime) fare. Following the steps provided by the two posters above will get you a credit which, as they said, needs to be used up (not just to pay for a new fare, but the flight completed) within one year of the original purchase date. The credit has to be used by the original fare holder, it can't be transferred.
If you won't be able to meet those two criteria, it doesn't really seem worth processing the change.