my airpods were stolen can i lock it

You can not lock airpods however you can use the "Find my Iphone" app which also works to find your Airpods, you can pinpoint their location if they are connected to the phone which you can send to your local police department to try and recover the stolen airpods.

AirPods only appear in find my when they are connected to the phone through Bluetooth.

AirPods do not have gps, WiFi or cellular radios. They do not connect to any network.

unless the original poster stayed within the 30’ range of Bluetooth and the battery holds out or is not placed in the case, they cannot be tracked.

No.