Simplify the following text for a Grade 10 native English-speaking person.
Original: Lucy later attempts to return to Narnia via the wardrobe , but the Professor tells her he has been trying for years , and they will probably return to Narnia when they least expect to .
Simplified: Lucy later goes to the wardrobe because she wants to return to Narnia , but the Professor tells her he has been trying for years , and that the wardrobe will probably not work again .