1. Immediately contact the airline's ticket counters at the airport.
If you arrived after check-in closed, first approach the representatives of the airline operating the flight.

2. Inquire about the possibility of late check-in.
Some airports have counters for late passengers. If the airline provides such a service, you may be able to check in for an additional fee even after check-in has closed.

3. Clarify ticket exchange conditions (NO-SHOW).
Most carriers prohibit ticket exchange in case of a no-show (NO-SHOW), but in some cases, it is possible — conditions depend on the fare and airline rules.

4. Check the possibility of a refund.
After the flight departs, most airlines do not allow a refund of the ticket cost.
To find out your fare rules and refund possibilities, contact Customer Care. To do this, on the order page, click the "Refund" button and submit an application.
If a refund is provided (sometimes only taxes are refunded), we will inform you of the amount to be refunded.

5. Be prepared to purchase a new ticket.
In most cases, if you do not show up for your flight, the ticket will be canceled, and you will need to purchase a new one.

Important

If you did not use the "outbound" flight on a single "round-trip" ticket, seats on the return flight may be automatically canceled by the airline's system.
Some carriers have exceptions — you can find more details in the article "Preserving subsequent flights when missing a flight".