Complex sentence: He left the UK to go back to the United States and disappeared from show business for a length of time, studied hypnosis and meditation, hung out with The Beach Boys and recorded some music with them that was never released.
Split into simpler sentences: He left the UK to return to the United States and disappeared from the music industry for a length of time. Washington studied hypnosis and meditation, made acquaintance with The Beach Boys and recorded some music with them that was never released.