THY Lost My Backpack on the Flight, Filed a Lost Report But No Response Still

During my 05:40 flight from Istanbul Airport to Malatya, I had both a suitcase and a backpack. My backpack got lost. We filed a report at Erhac Airport. They said they would inform me, but I haven't received any updates. Around 21:00, I called THY to express my concern and filed a complaint. Ten minutes later, I received a call saying my backpack was found and that I could pick it up by 00:00. I don't have a car. My wallet, cards, driver's license, and all my personal belongings are in my backpack. I don't understand if I forgot my backpack or if I have to come and get it myself. When I contacted THY again, the customer representative was not helpful at all and told me I had to pick it up myself. I don't understand why I have to bear the consequences of this issue when THY is responsible.