You can file a "CIVL SUIT" in the Civil Court of your Jurisdiction/Town/Village of your residence.
Civil Suit can be filed on the basis of "Documentary Evidence" i.e. Your Educational Certificate/Election Identy Card, which ever are evident for date of Birth.
This Civil Suit can be filed by making the Two Opposit parties:
First : TO WHOME SO EVER IT MAY CONCERNED
Second : Passport Officer of Tamil Nadu ( Proforma Party)
After taking your suit on file Magistrate will order for General Public Notice in any news paper, and on the next date of hearing he will take your statement on oath and on the same day he will pass Order for Change of Birth Date as per your documentary evidence. (It doesn't mean that within short period ordr will be in your hand, but it will take time as per procedures of the court )
So you can contact your local lawyer ( means a lawyer near to your town/village)
Court Fees will be "nominal" plus Advocate Fees
By the Court order you can apply for change of Date of Birth in your Passport.