Try listing volumes with diskpart and mounvol like:
DISKPART> list vol
This will show all volumes in your system and logical drive letters assigned to them.
Judge what's your 2nd WD drive that's not showing in Windows Explorer by the Size column.
If a volume does not have an assigned drive letter, run
DISKPART> sel vol n
DISKPART> assign letter=NEWLETTER
Where n is the volume number displayed in the Volume ### column of the list vol output, and NEWLETTER is the letter you want to assign to your partition that is not showing in Windows Explorer.
If you don NOT know drive letter of a desired volume and do not want to assign a drive letter, you can access volumes without doing it just by knowing their GUIDs.
Type exit to quit from diskpart if you have DISKPART> at your command prompt and run
to display GUIDs of all volume guid present in your PC. Those volumes that are listed as
*** NO MOUNT POINTS ***
are those that do not have any drive letter assigned to them.
Copy their GUID address such as
and paste into the Run dialog box (press WindowsKey+R to open it), then hit Enter to display the content of this volume in Windows Explorer.