Dear aspirant
At first lots of congratulations for your results .

I can guess your score is about 40 and rank is about  290000-300000 .According to trends of previous years and this year's JEE MAIN cut off I am afraid to inform you that your chances of getting admission into colleges NITs and IITs are almost negative. However You can try in state level counselling and private colleges . But if you have any other category rank like ST , SC there may be chance for you .One thing is  important that admission in those above mentioned category entirey depends upon that particular category rank , not the All India rank.
you can check previous years cut off
https://engineering.careers360.com/articles/jee-main-cutoff-for-top-nits
check your chances here
https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer

Best Wishes.