Complex sentence: Hepburn, a close friend of Barry, had appeared in the play on Broadway, and bought the movie rights (with the help of her ex-boyfriend Howard Hughes), and successfully restarted her previously flagging Hollywood career with the film version.
Split into simpler sentences: Hepburn, a close friend of Barry, had appeared in the play on Broadway and bought the movie rights (with the help of her ex-boyfriend Howard Hughes). She successfully restarted her previously flagging Hollywood career with the film version.