Earlier i was able to access the NTFS formatted External hard drive in my Mac 10.9 as read only device.
While trying to make the external NTFS drive writable i screwed up by unmouting it
diskutil unmount /dev/disk1s1
Later when i tried mounting it again it failed
diskutil mount
Volume on disk1s1 failed to mount
Best Answer
Following the unmount you should also eject the disc before unplugging it.
Alternatively you could use the usual methods: eject via finder, via dragging the drive icon into the waste bin, or with third-party apps like Alfred or Launchbar.