Please refer to the following information, so that we can direct you to the relevant authorities:
All identity papers, credit cards and items found in the public area (before security control): Police Grand Ducale, +352 244 18 5100
Items found in planes:

• Books, glasses, clothes: Luxair Baggage Assistance baggage.claim@luxair.lu, +352 2456 5003
                                                                                               
• Valuables, such as jewellery, electric and electronic devices: Luxair Baggage Assistance baggage.claim@luxair.lu, +352 2456 5003

Items found at the airport:

For items forgotten or lost at Luxembourg airport facilities,  please contact the Lux-airport via the following link : https://www.lux-airport.lu/services/lost-found/

For other items lost at an another airport, please contact the airport itself via their website.