World destroyed

Hey i tried to play my beta world to transfer it to the anvil loading version and it said do you want a back up i said yes it backed it up i got into the world my base was completly gone it was ocean but some other parts of my beta world where still there i don't know why its only that my base spot is gone and i went that on the backup version and its the same its destroyed too so my world is completly dead can u help me on this?

Please help me on this