If your original name is Kehsav then you have to change your name legally. For that you have to contact a lawyer who can guide you out in changing the name and after that you have to change the name in every document be it your Aadhar ID or Marksheet. Now if in 10th class you have your spelling mistake to be Kehsav then you have to edit your information from the council/board and on editing it you can finally get it in class 12th registration. For this procedure you have to contact your school authorities.

I hope this answer helps. All the very best for your future endeavors!