Process of joining back after sabbatical leave

Hi everyone one of my friends.. returning from sabbatical leave he went for MTech under machine learning and all.

Can anyone of you please guide me on this like how and what is the process for that. The current situation is like is not able to contact to any HR or not when is base location is Indore I guess..

Also can someone please confirm that how much height he can expect after completing mtech from tier 2 college