The NeverEnding Story (1984) on Netflix

Chased by school bullies, reprimanded by his father for daydreaming too much Bastian is lost in his own world. Bastian escapes school bullies one rainy day by hiding in an old used book store. After explaining his predicament to the old clerk Bastian notices a large leather bound book with a symbol of two snakes intertwined into an emblem. Soon after the clerk warns Bastian that this book is not for him Bastian, rushes away with it "borrowing" it, while the clerk is in another room. Taking refuge in the attic of his school Bastian opens the book, and a world of fantasy. Learning that the wonderous, beautiful land of Fantasia is being destroyed by a terrible "Nothing" Bastian is taken deeper into the story. Soon discovering the ChildLike Empress is deathly ill, the cause; she needs a new name. A young warrior named Atreyu is called and Bastian follows his adventures, unknowing that he, himself is slowly being written into the mysterious book. Soon realizing that he is now written in the book Bastian realizes that the only one who can save Fantasia is him.