You please contact the school in which you have studied your 10th class. You give them your request for correction in writing. You have to attach your tenth class certificate as well as a copy of the proof to show your father's name correctly. Submit the same in the school. Take a copy of the application and get the acknowledgement as proof that you have submitted the certificate for correction. Keep one or two copies of the 10th certificate duly attested by the HM of the school for your reference. If they object to taking your application as it is delayed a lot then the only way for you is to get the affidavit made. For that, you have to contact a good lawyer in your area and he will guide you accordingly.
In that case you have to go for legal affidavit. Please contact a lawyer who will prepare it in the legal format and then you have to sign it in presence of a magistrate in the court. The magistrate will also countersign it under his seal. One thing which is very important is that before signing, you must yourself check the typed legal document for any spelling mistakes in your name or father's name and other details about you. This is necessary to ensure that no confusion arises when you present it for verification at the time of counselling/ interview.
Please remember to affix all the supporting document with this affidavit as they will form a part of it.
I am not very sure whether the notary affidavit will do in this case. You have to confirm from the lawyer or the court office about it. There are certain matters where notary affidavit is accepted but for any name mistake in educational certificate that may not be admissible. Anyway, this you will have to find with your lawyer as they know the latest practices going on in these matters.
Knowledge is power.
It will be better if you contact a lawyer who has tackled this type of things earlier. Experience matters in these things and try to get an experienced lawyer who can make the legal documents correctly.
Thoughts exchanged is knowledge gained.
@ When your 12th and Graduation certificates are correct with your father's name intact, your 10th certificate will not be demanded and considered. In all your communication and documents, write your father's name as Gurcharan Singh only.
No life without Sun
Dr. Paresh B. Gujarati.
'I'mprovement always begins with 'I'.
Don't neglect. Sometimes small mistakes only will cost heavily. These days there is a big competition for government jobs and by any chance, somebody gets disqualified after getting the selection for the post for a small reason it will be painful. So please be proactive and take the action immediately. Already you delayed the matter a lot and now at least be fast enough. I wish you all the best.