You will need to notify the operator where the incident occurred.
If it occurs on the land segment, you should contact the ALSA Customer Service Centre or AVANZA Customer Service Centre.
If you leave something behind on an Iberia plane or in a VIP lounge, from the second day you can search for it from lost property.
If your checked baggage is lost on a segment operated by Iberia, follow the instructions on the baggage incidents page.
To find belongings left at the airport (boarding gates, controls, etc.), contact the lost and found office at the airport in question.