My Book for Mac does not show up in Finder

I have a MacBook Pro (Retina, 15-inch, Mac OS X 10.11.6) and I have my My Book connected by USB and power adapter connected to wall. Just wondering why it doesn’t show up on my laptop at all. I’ve tried restarting my laptop and the external hard drive, but nothing. I just bought the external hard drive, too.

Hi, was it working before? Did you change USB cable? Did you change USB port? Have you tried using a different computer?