Hi sjn, and welcome to cruise-chat.com. I am sorry that your first post was on the topic of lost luggage, and hope that it is found soon.
Same thing happened to my in-laws years ago, andit was returned to them. (Different line -- someone else had taken their bag mistakenly and contacted the cruise line as to how to return it.)
Penny's advice is excellent. Do you have the paperwork Penny noted? If not, perhaps someone who disembarked in LA (San Pedro?) recently can share it with you.