I have a 64GB USB drive that was unplugged halfway through formatting it, and now it isn't recognized by Disk Utility. diskutil list also doesn't bring it up. I have tried formatting it on a Windows computer with no luck either. It gives an error that it cannot be formatted. Windows at least sees the drive, but Disk Utility doesn't at all.

Are there any low level solutions that might work to re-format the drive or is it probably a goner that would need to be replaced?

  • Out of curiosity, are you running El Capitan as your OS? It's Disk Utility is generally regarded as broken, and I've found several times that using the old Yosemite Disk Utility works where El Capitan's does nothing. There are instructions for getting it here.
    – Testing
    Sep 16 '16 at 17:38
  • Thanks for the information! Yes, I am running El Capitan. I don't quite feel comfortable running through that procedure on my computer, but that's good to know it could be an El Cap issue. Do you happen to know whether things have been improved in Sierra? Sep 20 '16 at 14:15
  • Yeah, unfortunately it's not a very user-friendly solution. :\ The diskutil command line tool is as broken as Disk Utility for me so I eventually broke down and did it. From what I've read in review analyses, they have fixed some known Disk Utility issues in Sierra and done some more redesign, but I don't know how much of an overhaul it was. So it might be worth trying, but I don't have Sierra yet so I can't say for sure.
    – Testing
    Sep 20 '16 at 15:10

If you have the ability to burn an .iso and boot a livecd, Gparted should be able to format the USB drive.

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