When does Danny Phantom return?

Danny Phantom is an American animated superhero action adventure television series. The series follows Danny Fenton, a teenage boy who, after an accident with an unpredictable portal between the human world and the "Ghost Zone", becomes a human-ghost hybrid. Danny is aided in his quest by his two best friends Sam Manson and Tucker Foley, and later, his older sister Jazz, who for most of the series' run are among the only people who know of his double life. The show aired on April 3, 2004, right after 2004 Kids' Choice Awards.
Daniel "Danny" Fenton, a 14-year-old boy living in the small town of Amity Park, lives with his ghost hunting parents, Jack and Madeline "Maddie" and his overprotective but caring sister, Jasmine "Jazz". Upon pressure from his two best friends, Danny decides to explore the Ghost Portal created by his parents in their attempt to bridge the human world and the Ghost Zone (the parallel universe in which ghosts reside), that when plugged in, failed to work. Once inside, he inadvertently presses the "On" button (which his parents naively failed to do), thus activating the Portal and infusing his DNA with ectoplasm, transforming him into a half-ghost.