All you folks who loved the movie "Once," get thee to "Sing Street." They're both the lovely, unassuming work of writer-director John Carney, and they're both sweet paeans to the power of music. Here, in 1985 Dublin, teenager Conor (a pitch-perfect Ferdia Walsh-Peelo) is struggling with his parents' disintegrating marriage and with the angst and bullying he faces at a new school. He meets a girl (Lucy Boynton) and creates a band to impress her. The oldest story in the book, yes, but Carney and his cast give it heart and humor. Special due must be given to Jack Reynor as Conor's music-Yoda of an older brother; keep an eye on that actor.