My left earbud is not functioning but my right earbud is wokring

Hi

First I would check that they are both charging in the case by letting the little pop ups appear so that you can check this

After that I would put both earbuds back in to the case and hold the button on the back to reset them and re-pair them

If that doesn’t t work make sure that they are on the latest firmware version

You can check this by going into settings>Bluetooth>Then clicking on the (i) icon

If it’s up to date the version should be 4E71

If all that doesn’t work I would get in touch with apple support if take them to your local apple shop or authorised reseller

Hopefully this helps

Any more questions please ask

Thanks:-)