i got 2321 OBC-NCL RANK in b.arch but i did't got seat in any NIT? What is the reason behind this?

Hello
For this year the results will be declared on 15 the may 2019.
Talking about that why you didnot get seat.
As there are only 946 seats in nit s and other colleges ( in which you can go through josaa).
And number of candidates is more .
Previous year cut offs is near about 1500 for OBC category in outside state quota .( Check last year's cut offs ).
So it depends upon the other students and choices they fill.
So good luck