See for the correction of names in registration certificate as well as marksheet you need to contact your school authority. For most boards, the schools have forms which you need to fill up and submit it to the officer in charge as instructed by the school. Now this takes 3-4 months and after that you will get the corrected documents from your school only. So you should contact your school authority and for such cases they have all the resources to get your problem solved.

If your school is reluctant or not helpful to you then you should contact the Education Officer of your district and get it discussed. The EO will guide you or instruct the school authority to solve your problem. So don't worry and just contact your school at first.

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