(Henderson, NV) — The lines are up and running at Zappos.com. The Henderson-based online retailer reopened its phone lines on Friday, just days after a computer security breach. The lines were shut down so that customer service workers could answer customer e-mails. Zappos officials say a hacker accessed the company’s Kentucky computer center, compromising the personal data of up to 24-million customers. CEO Tony Hsieh says the FBI is investigating.