If you miss your flight you should immediately seek assistance with the nearest airline customer service representative.
If you miss your flight due to circumstance that could have been prevented (i.e. sleeping in or not budgeting enough time for check-in/security wait lines/time), the airline may allow you to fly stand-by on a later flight. Be forewarned: some airlines have implemented “same day stand-by” fees. These fees can vary depending on the airline.
Also beware that airlines can suspend your ticket if you do not show up for your scheduled flight. This usually happens within 24 hours of the missed flight. If you miss your flight, you are considered a “no show” and the ticket purchased loses all value.
If you find out that you missed your flight, you can also call the airline and plead your case with them. Depending on the representative, they may open the ticket up for you to use for a future flight. (It’s always worth a shot!)