"Alfred Hitchcock Presents" Whodunit (1956)

Recently deceased mystery writer Alexander Arlington appears before the recording angel in heaven. All goes well until he learns that his death was a murder, rather than a heart attack, as he had imagined. He receives permission from the angel to live his last day over again, so that he can find out who killed him. Back in his home, he relives a bitter fight with his assistant, and is certain that the assistant is the murderer. But when his nephew makes some threatening statements, and then he catches a glimpse of his wife warmly kissing a male friend, he starts to realize that almost everyone he knows has a motive for killing him.