Plot missing from LR khatian

Hi, my name is Syed Ahmed, I am staying in Siliguri, West Bengal. My query is my grandfather has a land or piece of parcel, measuring 3.78 acre of land , recorded in RS record of rights ( khatian), my grandfather died sometime in the year 1969. After that his elder son ( my uncle ) look in the entire property or land .. and in that land some people used to cultivate and whereas in few plots it's mention ( bargadar) in LR record of rights. And I came to know that from the current LR khatian many plots are missing and it is reduced to 1.32 acre out of 3.78 acre. Where as my grandfather did not execute sale deed or execute any deed. And the important point is that in my district coochbehar I cannot search documents in sub register or ADSR whereas it is was burnt in the year 1973. But I can search from 1974 till date but without information of deed number or date how can I search, and I also take all the missing plot information and I found many names and from my family no one is cultivating that land neither anyone produce us adhi/ bhag . Now how can I know that those people mutate the land and how to know about there fraud deed( assumption) i am confused where to approach and how to fix it .. and how can I evict them from my grandfathers property.