Try to get your AirPod back
If your AirPods are mixed up with someone else's AirPods, you'll both get an alert that says "AirPods Mismatch." Use the Find My app to locate your missing AirPods and play a sound to help you identify which AirPod is mismatched.
Replace your missing AirPod
If you can't find your AirPod, you can get a replacement AirPod from Apple Support. Just find the serial number of your AirPods, then contact Apple Support.