JEE

First solve NCERT books and then solve question banks.
Prepare physics from HC Verma and maths from RD Sharma if you want good control over these two subjects.
Good luck.

NIT Warangal
NIT Surathkala
MNIT Allahabad
VNIT Nagpur
Sardar Vallabh Bhai National Institute of Technology Surat, Nirma University Ahmedabad
MNIT Jaipur
IIIT Hyderabad
IIT bangalore
Indraprastha Institute of Technology, Delhi.

You can download the answer key of JEE on Google by different coaching solutions.

If you are trying for JEE since two then you know better about your knowledge and skills. Now, you have lost your two years, so my suggestion is to get admission in any another good college for engineering.

Yes, RD Sharma is a good book for class 11th and also, it will help you in preparing for IIT JEE. But you can refer to other books like ML Khanna and SL Loney.

If you want to do engineering only then you can apply to other colleges. Also, you can go for B.Sc or B.Sc honors.

All NCERT books, RD Sharma and HC Verma.

Dear Vyom,
For your kind information, I want to tell you that while evaluating the JEE rank, 40% weightage is given to your marks scored in the intermediate and 60% weightage is given to your entrance exam score.
But for your knowledge, I want to tell you that your seat in any good college depends on your rank and the cut-off of that particular year. Every year cut-off for different colleges varies. So you simply have to participate in the online counseling and fill your choices as government institute on priority basis.

Not cracking JEE Mains is not the end of the road. You still have following options available with you:
(a) Engineering from state or private colleges
(b) BCA
(c) B.Sc IT/CS
(d) B.Sc Physics, Chemistry, Maths or Statistics
(e) B.Arch
f) BBA, BMS, BBE, etc.
(g) Five-year integrated law
(h) NDA
(I) SCRA
(j) Merchant Navy
(k) Fashion Designing
(l) Hotel Management
You can also change your stream to commerce, economics, humanities, etc. You may choose any based on your interest to excel in the professional career. BCA may be a better option in comparison to generic B.Sc.

Yes, you will definitely get admission. Just wait for the counselling.
All the best.