From IMDb review:
Tom Nightingale, a writer of children's books, falls prey to a serious case of writer's block after the loss of his wife. He now spends his time reading fairy stories to his young daughter, Melissa. But they are not alone, for each night a real fairy, Crystal, listens in on the stories. Meanwhile, Tom's pet dog is keeping an eye on Crystal and one night decides to chase her. Crystal collides with a tree and is knocked out. She is suddenly transformed into human form and subsequently suffers amnesia.
Tom meets Crystal and eventually falls in love with her, much to the disappointment and disapproval of Melissa's teacher, Miss Martinet. The only trouble is Crystal has to return to Fairyland before The Collector can capture her and send her to the dark world. And she only has six days!
Can Tom find the spell that will save Crystal?