I have tried to change the priority of samba on run level 2 by renaming the S16samaba to S21samba.
mv S16samaba S21samaba
But when I reboot the server it starts before other services which are low priority like S12ntp.
I have also tried using update-rc.d command.
update-rc.d samba start 80 2 3 4 5
This command renamed S21samba back to S16samba. And it doesn't work.
I want to start the samba after all other services are started.
Please give me suggestion with the idea of priority of service in run levels.
The reason your approaches do not work it that they assume a system V init. Ubuntu does not use system V init. It either uses upstart or systemd depending on version. I do not believe either system uses run levels which is a tragic step back for such "advanced" systems.