What episode is after the drill in avatar?

You're likely referring to the episode where Team Avatar confronts the Earth King about the drill that's destroying the Earth Kingdom. This episode is called "The Drill" (Season 2, Episode 11).

The episode directly after "The Drill" is "The Guru", Season 2, Episode 12.

In "The Guru," Aang travels to the Spiritual Oasis to meet a guru who can help him unlock the last airbending ability: energybending.