Keira Knightley is not a musician in my knowledge base, but rather a British actress known for her roles in films like "Pride and Prejudice," "Atonement," and "Pirates of the Caribbean." However, I do have information about Keira Knightley's singing appearances in films. She showcased her vocal talents in the 2014 movie "Begin Again," where she played the role of Greta, a singer-songwriter. The songs "Tell Me If You Wanna Go Home," "Lost Stars," and "Like A Fool" are part of the film's soundtrack, featuring Knightley's vocals.