*Click on Start --> Run ---> type diskmgmt.msc and click on OK
*Right-click on WD Passport Drive --> Select "Change Drive Letter and Paths..." --->
*Click on "Add" button ---> Select your drive letter and click on OK
*Note : If the drive letter is already assigned, then try changing the drive letter by clicking on the "Change" button instead of "Add" button in the above step
*If the problem still persists:
*Click on Start --> Run --> type regedt32 and click on OK
*Registry Editor will be opened
*First backup your registry by going to File --> Export
*Then expand the following key:
*If you see any upperfilter or lowerfilters entries at the right side, simply delete them.
*Close the registry and restart your PC.