For example, if you have a ticket that does not allow for general refunds at any time, or in other words, you have a ticket that restricts the refunds in total, or until a date before the travel date. It is unlikely that you can request a refund.
After reviewing the General Conditions of Carriage of Turkish Airlines, I can not find a clause that covers reimbursement for illness or other medical reasons for the inability to travel. In this case, there is no automatic right to a refund. This is important for Turkish Airlines customer service, but they are not required to refund the tickets.
Depending on the coverage and policy, you may be eligible for travel insurance. However, you may be in a difficult situation if you do not contact them, if your entire family has decided not to fly – that is, the insurance company often wants to discuss something, and it may not cover the voluntary decision not to fly any other than the involuntary decision not to fly.
Depending on the Class of Ticket you have purchased, you may be required by Turkish Airlines to request a credit for the residual value of the Ticket in order to use it for future travel. Many airlines believe that under certain circumstances a ticket may still have value when the travel date has passed.