How to correct my name on educational certificate?

You have raised a question of mismatch of your name in your educational certificates including the 10 th and 12 th mark sheets. You have not indicated whether such mismatches are uniformly in nature in all the certificates.
You need to take your initiative with your personal meeting of the headmaster of the secondary school and verify your name in your school admission register. If the name entered in the school - register is correct, it must reflect on your certificate and mark - sheet of class ten. If the deviation has occurred from the board - level, you need to write an application to the secretary of the Board with the forwarding note of your headmaster for the corrections. Once the same is corrected from the office of the Board, you need to take a similar step for all your certificates.

The certificates should have the correct name. If there is a mistake, definitely there will be problems for higher studies, job and other issues. One should take corrective action.
There are two ways to address this problem. The first one is through the school in which you have studied. You have to contact the school administration of the school in which you studied and give them an application asking for correction in the mistake. You have to attach present original certificates and a certified copy of proof of your name. If any other details are asked for by the school are also to be submitted along with your application. The required fee is to be paid. The school will forward your application to the board and the board will do the needful.
It may take around 2 months to complete the process after you submit the application.
The second method is to make an affidavit. You have to contact a good advocate in your area who will explain the method that is to be adopted for this and he will do the needful. This process will be fast and the whole process of obtaining the affidavit may take about 15 days. But the first option is the best in my opinion.

We should furnish our name, father's name etc., with correct initials, spelling, surname etc., when we give at the time of admission or at the time of submitting examination application through the school. The certificate issuing authorities cannot be blamed for spelling difference as many people do have their names with different spelling in the thought of numerology and practice of their own area. In Pondicherry area people write Mourougan for Murugan. In Kerala Mani is written as Moni. In Bengal area Vasu is written as Basu.
It is common to have some mistakes while entering name/s in certificates and it is our duty to check while receiving. This may be due to the steps of both sides. While furnishing our name in application we should take utmost care as a)with or without space b) when we follow some numerology adjustments.
To correct this we have to approach the concerned authority IN PERSON with relevant documents without delay.
Subsequently we should have all certificates, Government IDs like Aadhaar etc., with similar name and spelling.
It seems to be a difficult one in your case as your school is not existing now, you can approach local government educational authorities for getting correction in your certificate. When you are going there you should take the following with you:
1.The school documents, any, whatever you possess.
2.your present aadhaar card
3.any relevant document/s which has your name with correct spelling and surname.
There are chances to get your certificate corrected.
Alternatively, you can approach local advocate with notary who will prepare an affidavit with notary signature for such correction.