You can try a few easy steps to fix your drive that won’t mount on your Mac:
- First, try the obvious. Try another USB port on your Mac.
- If that works, great! End of story.
- If not, turn of your Mac.
- Turn it on and hold the shift key as soon as you hear the chime.
- It will check the startup disk and then hopefully fix your external drive
- If that doesn’t work, you will probably have to bring it to an unmountable external drive Mac specialist.