please check registration rules of your state . there must be clause covering unforseen events like fire , floods for instance karnataka registration rules contain following clause .

Where due to fire

tempest, flood, excessive rainfall, violence of any army or mob or other

irresistible force any, or all of the books specified in sub-section (1) of

Section 51 are destroyed, and the District Registrar is of the opinion that it

is necessary or expedient so to do he may, by order, direct such books as

the thinks fit to be reconstructed in such a manner as may be prescribed by

the Inspector General of Registration and Commissioner of stamps from

time to time.]

When a law is passed it does have a provision of dealing with such unforseen events. You may file a RTI to the District Registrar asking him to furnish to you a copy of the rules made by the government in such behalf. Once you obtain the rules you may then proceed to get the record reconstructed in the manner laid down under the rules.

If you do not have the requisite documents in your possession then it will not be possible for you to prove the antecedent title of the land, which implies that registration cannot be done.

you need original documents of entire holding area to prove ownership of the said land in your possession . if original documents have been lost have you filed any police complaint . you can obtain certified copy of said documents from the registrar office