H.R. Pufnstuf (1969)

Season 1: Episode 17

While running from the witch, Jimmy trips and falls getting knocked out. When he comes too he can't remember anything not even his own name. The rest of this story is a series of flash back as first Pufnstuf and the good guys try to jog his memories. When Jimmy wanders off and meets up with the evil trees, they bring him to Witchiepoo who then gives it a shot. Jimmy finally remembers when pieces of the castle ceiling hit him on the head