Why are my airpods not charging at all?

Bad Lightning cable, bad charger, switched-off or bad wall outlet, fluff or debris in the Lightning socket of the case, gunk on the AirPods case rim preventing it from fully closing, gunk inside the case or on the AirPods blocking the contact between the AirPods and the case, or failed hardware.

Here is what the folks at Apple recommend doing: If your AirPods won’t charge - Apple Support