This question is a bit strange. Birth certificates issued by municipal bodies are the most authentic ones, as the record is created immediately after the birth of the child. While admitting the child to school, parents often put some arbitrary date as DOB and this continues for ever in all subsequent records.
In the above case the actual DOB recorded by the municipal body is a year earlier. It can not be changed in the normal process at all. The other later records can be changed to be aligned with the birth certificate of the municipal body, but that too with all concerned departments with prolonged correspondence.
Also a difficulty would arise, since in India, parents name the child only much later and so the name of the child born on any particular date is not recorded at all in the municipal records, just mentioned as male/female child with the name of both parents.
If you are sure that your real date of birth is 0f 1991 and not of 1990, then a question would arise as to whose birth is recorded in 1990 and why so. Is it any other child born earlier and not the querist?
If there is adequate proof of personal witnesses, hospital record, immunisation record etc of the fact of the child being born actually in 1991, then the following is suggested:
1.Apply for certificate of birth to the municipal body of place of birth, duly mentioning the date of birth of 1991, and both parents name and actual spot of birth, hospital/house with address.
2. Use prescribed form, if any and pay the prescribed fees.
3.Application will be declined mentioning the reason that no such birth is recorded in the municipal records.
4. File an original suit at the civil court of jurisdiction at that place, arraying the municipal body as the defendant, with prayer for recoding the birth and issuing certificate.
5.Ensure service of notice of court, as expeditiously as possible on the municipal body.
6.On the date of hearing a standing counsel of the municipal body will appear for the defendant.
7. File your affidavit of evidence, and affidavits of two or three witnesses, of whom preferably one person be a parent or a blood relative elder to you.
8.There will be a perfunctory cross examination by the municipal body's counsel.
9.You will get a decree of the court, in your favour in normal circumstances.
10.Serve the copy of the decree on the municipal body, register the birth afresh, and then apply for issue of certificate aghainst prescribed fee.
After getting the certificate, start the long correspondence with each department, for correction of records.
Time lag in court case would be six months to one year depending upon the place and workload of the court. Lawyer fees may range from Rs.5000/- to Rs.25000/-. For this a junior lawyer would do.