the battery and mic problem
the left hand side one got problem
AirPods (1st generation)
Question marked as
Did you already try the troubleshooting tips in this article?
If your left or right AirPod isn't working - Apple Support
In case you did and the AirPod is still not working correctly, you will have to get it replaced.
Use this link as a start:
Replace your AirPods or charging case
This article describes, how to pair the replacement to your device again:
Set up your replacement AirPods or charging case - Apple Support