Karen O breaks from her rocker roots to deliver a more sentimental musical venture.

You may remember that Trent Reznor, lead singer of rock band Nine Inch Nails, won an Oscar a while back for his soundtrack to “The Social Network.” Reznor is continuing his foray into film with his newest project, a soundtrack for the film adaptation of “The Girl With the Dragon Tattoo.”   Reznor teamed up…