I have the Exact Problem you facein … My WD 2TB Essential with power adabter , bought it something like 3 months ago , it was perfect.
once a day, i was near the Laptop when it made the sound of USB un-Plugging … i checked , my WD HDD wasnt there on Disk Drives , i woundered !
Rebooting the Laptop fixed the problem for Only 4 Minutes … The Cable is perfect and Changed the Adabter and faced again the same problem .
Even Changing the Laptop wont make any difference.
Now , even if i un-pluged the Power Supply Cable out of the Device , sometimes it works and sometimes doesnt … this is not a solution. its a temporary one for only 2 - 5 minutes
actually, i use bittorent alot . but i have never set my WD 2TB Essential HDD as a download location being afraid to face such a problem.
i guess its a hardware problem from the inside… cuz if you think about it , it was perfect and nothing changed in my computer settings, but suddenly its not Spining up and the computer cant detect it …
WD Community … We need help over here , files inside the HDD are very important … and unfortunetely, they are not backed-up … but im sure they are still there … the proble is with HDD Spinning and Detection.