If WD Smartware is not finding the disk the drive could be not recognized or defective. First make sure the drive is plugged properly ( if you have a desktop computer use a usb port located on the back, if you have a laptop make sure to plug the cable directly to the laptop)
Go to computer to see uf the passport drive is there, if not go to Disk Management. (Start > right click on Computer and select Manage, on the Computer Management window click on Disk Management the second option from bottom to top)
Verify is the drive is showin healthy or unalocated, if the drive is healthy it means the drive is fine just uninstall, restart the computer and re install WD Smartware.
If the drive is unalocated you will have to format the drive in order to use it again ( I hope that's not the case).-