I got 75 marks in mains, I am OBC,can I get any NIT college

For 75 marks in JEE Mains, rank will be very high to get a seat in NITs. But you can try for home region, still the chances are less. If you compromise with the branch, try for new NIT's and be patient until the last phase of counselling. Even if you don't get the seat there is one more chance of spot round. Meanwhile backup a seat in best local engineering college.