Help, I'm a Boy! (2002) on Netflix

In Hamburg, an aged sorcerer is searching for a replacement. Freddie, who's about 12, finds the wizard's book of spells and knows enough to read a few lines to his friend Emma. She repeats the lines adding exasperation about Mickey, a boy who's often mean to her. The next morning, Mickey finds himself in Emma's body, and Emma finds herself in Mickey's body. The wizard tracks down the book, takes it back, and disappears, leaving Freddy with no way to reverse the spell, which becomes permanent in 54 hours. Freddy, Emma, and Mickey must work together to search out a solution, while making discoveries about sex roles, courage, friendship, and each other.