Dear Rohitsaroha
To enter into premium institutions like Not or IIT you should qualify the JEE first. They consider these score for admission. So have an hand on preparing for it and I hope you get your exams go well. Have some references for preparation from the internet. Hope you find this helpful.
All the best for your upcoming attempts !

hey,

diploma holders can take admission into IITs that too in first year , diploma holders are supposed to appear for both JEE Mains and JEE advanced then only you would be eligible to get admission in IITs  even if you have cleared JEE mains and didnt manage to clear advanced no NITs will give admission to diploma  holders

i hope this thing is clear to you

all the very best!