Need lawyer help to get duplicate sale deed document of a missing sale deed

There are many lawyers in your district and contact one who is near to you.  Or you can directly go to the sub-registrar's office and apply there for a copy of the document.

Sir, Duplicate copy requires FIR, paper ads and attach them to SR office.. You know it well, so seeking help of Advocate

To my knowledge, no reason needs to be given for getting a certitifed copy of a registered conveyance deed. Nowadays, at least in Kerala, you can apply for the same digitally.

Is it a legal query to be considered and obliged by experts scattered all over world on this site ???

To apply for certified copy you don' need any FIR or advertisement, just application with your details to show that the name in sale deed is yours.