WD Element 2t - has lost letter

I was trying to reformat to Fat32 via WD Quick Formatter and got an error so I went back to my files to find the drive and could not see it any more.  The HDD appears to have lost its letter - how do i allocate a letter to it?  Im using Windows 7

He, check the link below for the steps.

How to change the drive letter assignment in Windows 8, 7, Vista, XP or 2000