(1) first of all need to start machine in single user mode which you can do by pressing
Command + S at system start up
it will start machine in command line mode, as its process will complete you can see
:/ root #
now type the command
(2) /sbin/fsck -fy
after that
(3) /sbin/mount -uw /
(4) launchctl load /System/Library/LaunchDaemons/com.apple.opendirectoryd.plist
(5) passwd root
after changing password of root successfully you can use any of the below command
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