Binu - are you wanting to automate this process with TES?
There is a windows cmd command "net stop" and "net start" you can use to stop and start a service.
You will need to work with your windows admin or look online for a command line way to change the service to manual and to start the defrag.
There is a shutdown command that can be run from cmd. It has a switch to force the reboot.
You might also check out scripting with WMI.
Hope this helps,
Michelle