Mac Book White stopped recognizing my WD Passport

I had a similar issue on my iMac.  The drive was getting power because the lights were on and I could hear the drive but my Mac couldnt see it.  Long story short - It turned out to be the power supply.  When I swapped out the power supply the drive worked fine.  I would have never thought that was the issue because the drive was definitely getting power.  This may have nothing to do with your situation but wanted to mention my experience.