How can/should I write an attestation letter for correction of a date of birth?
Welcome to the forum. :hi:
Please note my change above. You should always write complete sentences. That means starting with a capital letter, ending with an appropriate punctuation mark and making sure that your sentence has a main verb.
We don't write letters here for people. You should try to write the letter yourself, then post it in this section and then we will look at it. Please don't use real personal details (full names, dates of birth etc).