The Seven Year Witch Charmed : Season 7 Episode 16

Piper is attacked by demons and winds up in a coma, and as she hovers between life and death, her spirit meets a familiar face who wants to help restore Phoebe's faith in love. Phoebe, Drake & Paige rush to save Piper by attempting to locate Leo, who's memory has been wiped clean by the Elders in attempt to allow him to choose his own destiny: be an Elder forever or choose Piper, and become mortal.