Hello.

You did nothing wrong because a failure earns more knowledge than a successful person.

However now you have another chance why won't you make use of it. Think big like , how my life is going to be if get in IIT or NIT else you will be studying in boring local colleges where you will never find knowledge and freedom.

 A good strategy always considers all angles of the problem to know them well before solving it. Similarly, any aspirant must check the IIT JEE Syllabus, exam pattern to know what he/she is up against and then aim to crack it. Check the 16 steps to crack IIT-JEE, follow them to get a foot into the IITs. 

https://www.google.com/amp/s/engineering.careers360.com/articles/16-steps-crack-iit-jee/amp.

So keep motivating your self and go with the flow.

Hope this is helpful.

Good luck.