A file system is basically the way the information is stored on your HDD. So different operating system have different native file systems. Before I explain how to do this I will explain what went wrong in the first place. All drives can be formatted to work properly on both Mac and Windows. Please Note that there are GUI differences between Mac OS 10.0-10.10 and 10.11-Current (10.13 as of writing this).Hello GhostChz22, All My Passport drives are sold preformatted for either Windows or Mac but doesn't mean you cannot use them with a different OS. Choose the appropriate file system format: If you only plan to use to drive on Mac Computers then select one of the Apple Journaling options, if you plan to read and write the drive using anything other than Mac OS devices, I suggest ExFAT. Right click on the drive or any of the partitions and select erase.Open Disk Utility, an application you can find by typing 'Disk Utility' after pressing CMD+SpaceBar (or br clicking on your spotlight icon, a magnifying glass in the top right of the screen).Consider doing the same for any partitions you can access.

Located your Western Digital My Book and right click it.

Open Disk Utility (yes again, if you want other recovery software you may choose to use Disk Warrior or a deleted data recovery application).

However if there's enough data left the operating system can correct these errors. Some logical volumes (partitions (file systems)) become corrupt during plug and play or electrostatic phenomena.

Expand the Western Digital My Book drive on the left side and right click on the partition you wish to mount, select Mount.

Open the Disk Utility app located in /EXAMPLE-HDD/Applications/Utilities/Disk Utility.app or by pressing CMD+SpaceBar and typing 'Disk Utility' or by manually clicking on the Spotlight Icon in the top right (magnifying glass icon) and typing 'Disk Utility', or by opening your LaunchPad and locating Disk Utility.

Ext 1-2-3-4 are all read and writeable by the majority of Linux operating systems, FAT32-ExFAT-NTFS-ReFHS are all read and writeable by most Microsoft Windows operating systems. If there is data on the drive but your Mac device cannot read it even after attempting to manually mount the drive partitions, then I recommend plugging the drive into a computer with support for the file system being used on those partitions.

I recommend you try mounting any partitions first. With the limited information you have presented, formatting drives with Mac OS 10.0 (2001) to the newest version 10.13 (Dec 2017) has always been the same.

Reformat my passport for mac