my rank is 71549 sc category what are chances of my getting nit

Honestly speaking, with a rank of 71549 SC Category, there are zero chances of making it into any NITs. But if you hail from northeast states like Sikkim and Mizoram, the closing Rank for these NITs SCS category goes up to 10.5 lakhs under the home state(HS) quota. So admission to NITs is possible only if you belong to these states. Another option is to go for some private colleges/state government colleges that might grant admission on the basis of your JEE rank. Else, the last option is to take a drop year and score better next time.