Mixing up AM and PM or the wrong date happens more often than people admit.
Contact the airline immediately
Even if the plane has gone, tell them right away. Quick contact gives you more options.
Ask about standby and changes
Some airlines allow same-day standby or a paid change, which can be cheaper than a new ticket.
Check your fare
Flexible fares often allow changes, while basic fares are stricter.
Ask for refundable taxes
Unused taxes and fees can often be refunded on non-refundable tickets.
Prevent it next time
Check your itinerary twice, add the flight to your calendar and enable airline notifications.
For help, call +1-800-984-7414. See this what to do if you miss your flight guide for a full walkthrough.