AbhishekGoyal First of all nothing to worry because it was not your mistake..
Just look for what changes have been made in the exam pattern. Since You must have forgotten many things, You need to start by the initial point. Topics which you are sure of, leave it for later. Just work on those things which You think is hard..at this time you need inspiration too..and don’t worry 2 years gap is not a very long gap..you can still make it. Good luck.