Hello mounika,
If you have old one in your name there will be no problem.
If there is no caste certificate you have apply a new one you will get after applying 2-3 days. If need in one day you have to visit MRO in your area then you will get in one day.
I hope it helps you.
If still having issues regarding this you can comment in below.
Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile