When booking a flight, always consider purchasing insurance. While insurance normally only covers emergencies and not simply things like a change of mind, having insurance can be useful if you get injured or have a sick relative. If you need to cancel your airline ticket for one of these reasons and have insurance, first go through your insurance company and tell it you need to cancel your flight. Do this by calling the toll-free number on your policy. Request any forms that you may need to complete, and be prepared to present documentation such as doctor's certificates or death certificates depending on the incident.
Often airline tickets will be on sale or discounted. This is especially true for ones bought online or through third party vendors like Expedia, Orbitz or Travelocity. Discounted tickets are generally non-refundable, so while you will be able to cancel your flight, you won't be able to get any money back. This is why you should book a full fare flight directly through the airline, especially if you think there is a possibility that your plans may change. Full fare flights are more expensive but you normally have the option of date changes, location changes and cancellation with full refund. If you have booked a full fare flight contact your airline and follow their instructions on how to cancel your ticket, and hopefully you will receive a full refund.
A lot of people book tickets online and this is often done through travel companies such as Expedia and Orbitz. Canceling a ticket through these websites is normally quite a simple process because the websites have FAQ sections which cover exactly how to do this. Generally you just need to log in to your account, select your itinerary, and then click on cancel ticket. If you wish to get your money back for your ticket you may have to call the agency and speak to a customer service representative about your options. They may be able to give you credit towards future travel on their website.
When canceling a ticket make sure you cancel early. If you cancel your ticket far enough in advance you may be able to rebook for a time that suits you or get full credit so that you can purchase another ticket when things settle down. If you're ever not sure about exactly the correct procedure when it comes to canceling your ticket just call your airline customer service and ask them for advice as they are trained to deal with these situations.