Betsey Johnson won’t be cartwheeling down the runway this Fashion Week. The designer had a splashy birthday party and fashion show last season that included a performance by Cyndi Lauper. But the company announced yesterday it won’t present a collection at February’s Fashion Week. Betsey Johnson LLC last year filed for bankruptcy and was taken over by Steve Madden. It closed its stores across the country to focus on a new line to launch next month at Macy’s and other retailers.