"External Drive not mounting on MacBook Pro Retina"에 답변Hello. I'm not sure if I can help, but here was my situation. For some unknown reason my WD 1TB suddenly stopped "mounting." I'm using MacOS version 10.13.4 (High Sierra). I found one of my older forensic applications called Disk Arbitrator. The application recognized my WD 1TB external hard drive as "unmounted" and I was able to "mount" the drive using this application and I was able to subsequently make a copy of the drive (data) using a software copy program and then "restore" my original drive from the backed-up drive using the "restore" function in Apple's Disk Utility application. The Disk Arbitrator program was an older version (v0.2); I could not figure out this process using "newer" version of this program. BTW, because my drive would not mount on my iMac or MacBook Pro, Apple Tech reached the conclusion that the drive had to be bad and unfortunately I was going to loose all my data. Anyway, this worked for me and I hope it may help someone else.