What to do
Open the original booking confirmation and look for any mention of change or cancellation conditions. If the text is missing or too dense, contact the airline and simply ask what is allowed for your specific ticket. Have the booking reference ready. Online chat or email often works better than phone when you want a written answer you can keep.
Three options
First option is a free change. Some flexible tickets allow one date or time change without a fee if you request it early enough and seats are available on the new flight. The route usually has to stay the same. This is the best case and it does happen, though not on every fare.
Second option is a paid change. Most standard tickets fall here. You can move the date or sometimes the route, but you pay a fixed change fee plus any difference in the new fare. The fee can range from modest to quite high depending on how close the departure is and how full the new flight is.
Third option is almost no change possible. Many basic or budget fares do not allow date or route changes at all. In those cases the only realistic paths are to cancel and lose most of the money, or to keep the original flight and adjust the rest of the trip around it. Taxes and certain fees may still be returnable even on these tickets.
Cost
Free changes cost nothing beyond the possible fare difference if the new flight is more expensive. Paid changes usually add a fee between 50 and 250 euros or dollars, plus the fare difference. Non-changeable tickets often return only the taxes if you cancel. Always ask for the exact total before you confirm so the number does not surprise you later.
Summary
Airlines generally allow more than the online tools first suggest, but the room to move depends almost entirely on the original fare. Flexible tickets can give you a free or cheap change, standard tickets usually require a fee plus fare difference, and basic tickets often block changes completely. Check the booking details, ask the airline directly for your specific case, and compare the three paths before you decide. Knowing the common limits in advance saves time and stops the panic when plans suddenly shift.
