One AirPod not working
on some devices the right one isn’t working and in some the left isn’t even after resetting them.
Please following the troubleshooting at If your left or right AirPod isn't working – Apple Support
TIP: You have posted this in the Apple ID section of Apple Communities, you might have a quicker response next time if you post in Music as Airpods is a Music accessory, or the device you are using them with eg) iPhone.