Lost AirPod

Probably the battery is dead so the only way to find it is all the old fashiioned ways such as looking under furniture. If you cannot find it then you can get a replacement:

Replacement instructions for lost items are provided at the bottom of this support article "If your AirPods are lost: --> https://support.apple.com/HT207581 Neither the warranty nor AppleCare+ helps with the cost of Airpods that are lost.

'AirPods Service and Repair' lists replacement fees. Click here --> https://support.apple.com/airpods/repair/service

1. If you can't find your AirPod or Charging Case, or if something is damaged, get the serial number. Click on this link to discover how to find the serial number. --> https://support.apple.com/HT209371

2. Contact Apple Support for a replacement. Click here --> https://getsupport.apple.com/?caller=kbase&PGF=PGF32003&category_id=SC0298

(You may have to go to the support article in my first link for the special Airpod replacement service link if that one doesn't work.)

3. Learn how to set up your replacement.

Set up your replacement AirPods or charging case - "When you get your replacement, follow these steps to use your AirPods again." --> https://support.apple.com/HT207827

Please note that most people posting here do not work for Apple, we're just unofficial volunteers, users like you, trying to help others. We can only use our familiarity with Apple products and support documents to advise you as to what you can do to help yourself, we can't actually do anything for you.