Why is only one side of my AirPods playing audio?

When there is only one airpod working, then it is either a battery problem or a wiring glitch. Attempt to insert both air pods once more in the charging case and leave it some few minutes to re-synch them. Then disconnect and reconnect them to your device. The second thing to ensure is the audio balance setting on your phone since when it is either to the right or left, it may give the impression that only one air pod is functioning. Sound blocking by dirt in the speaker mesh can also be fixed by cleaning the mesh gently.