pipefitter,

It depends who you've booked with and what there terms and conditions are. With some airlines, even if you're booked a return flight, they're actually 2 single flights. Some they are on a return basis. I would look at the booking conditions of the airline you've booked with to see if you can change the dates, probably for a fee, or if you can cancel and rebook. It's difficult to advise further without knowing who you booked with.

Darren

typically you would also pay the difference between the cost of the original flight and the cost of the planned flight.