This is an extract from one of my own post on this community.
When the drive is not visible on explorer/Computer, open Disk Management utility and look for the drive corresponding to My Passport and right click and choose, make partition active. Then assign an upper order drive letter. (E.g… W for WD) Do not assign lower order drive letter such as E, F, G and H so on) Now open windows explore (You should see your drive here at this time) and click “Organize” and the choose “Folder & Search Options”. On folder options click “View” Tab and unchecked “Hide Empty Drives in Computer Folder”.
To open Disk Manager, Press Win Key + R and then type diskmgmt.msc on RUN dialogue box.