I was trying to reformat my My Book WD to use for Mac and I used Disc Utility to erase and reformat, but when I did that I got an error that said it failed, and now when I plug in the external to my computer, it doesn’t show up. Did I erase it? How do I get it working again?
Thread moved to WD External Drives: External Drives for Mac.
I suggest you to try again, I have provided a guide underneath:
Answer 3865: How to partition and format a drive on Windows and Mac OSX
Same question and solution is posted on the following link