In this situation, you can manually mount the external hard drive.
Sometimes, external hard drives cannot be automatically mounted in Disk Utility, even though Mac has detected the external hard drive. In other words, you didn't allow your external hard drives showing up in the Finder or on the desktop. Try quickly plug and slowly plug, sometimes it just works for no reason. You can do some basic checks to troubleshoot whether this issue is resulted from those factors. In addition, the following reasons may also lead to WD external hard drive not showing up or not working. If you can't see files on the hard drive on Machow to access data? You'll get answers here. In either way, your important data on this drive will become inaccessible.
Even worse, it may become unreadable on Mac computer. What's more, they are widely known thanks to their auto backup, password protection, and high reliability compared with other hard drives.
