Hey,
I am afraid to tell you that with such a high rank you have almost negligible scope of getting into any good college but then, it is not the end of the world to lose. Often when we lose all hope and think this is the end, God smiles from above and says, 'Relax dear, its just a bend, not the end".

So I would suggest you imbibe this positivity in yourself and taking a lesson from your mistakes that you did this year, apply it to your preparation and reappear for the exam next year.

All the best! 

You can check the cutoff from the career360 cutoff platform. But according to me you can't get CSE in any good  NIT with this rank whether you are from SC/ST category.

Dear Sourav,

You can check the cut off of JEE Main from the given below link

https://engineering.careers360.com/articles/jee-main-cutoff

Good Luck!!