If it so happens that you cannot fly at the previously scheduled time, but do not want to lose money for tickets, then there are several ways to do this. It will not be possible to do without losses, but it is possible to reduce them to a minimum.
It is necessary
To change your plane tickets, contact the ticket office of your airline or the website where you booked the ticket to clarify the possibility of canceling the trip and receive a portion of the money spent on the ticket. If you do not want to cancel, but reschedule your trip, find out if this can be done and if you will be charged some kind of surcharge from the airline. If you cannot use air tickets and the appointed date of travel due to the fault of the airline, then you have the right to a full refund of the cost of the air ticket, and, in some cases, to additional compensation for moral or material damage (if justified).
Otherwise, the change of tickets depends on which tariff you chose when purchasing. For example, the excursion tariff allows you to change any ticket even very close to the departure date, special tariffs, including discounts, on special conditions, on "hot" lines practically do not allow such an opportunity. Some fares provide for a ticket change, but with the obligatory deduction of funds from the ticket price as a penalty. Sometimes you can change your tariff, also some transport companies provide the ability to change air tickets to other types of transport or vice versa.
If the tickets have not been used, and the date of the trip has passed, such a case is considered individually. If there are valid reasons and documents confirming them (illness, refusal to issue a visa, etc.), in some cases it is possible to get a part of the price of an unused ticket back.