hello Nisha,

As you have got 21986 AIR rank. The reason for you not getting selected can be your marks and rank.

Maybe, the college in which you have submitted your form or applications have higher cutoff then your score.As in every round the cutoff slightly changes by some marks every year and you are not selected in round 1 and round2, there can be a chance for you to get selected in round 3 as cutoff decreases in every round.

selection is not confirmed but you have a chance to get a seat.

hope this may help you.