Before you open any backup copies, make further backups!
It sounds as if the project opens OK and allows you to edit.
What about if when creating the output you just generate but do not
publish? Is that generated output entirely correct?
You are saying that only old topics are publishing but they
were there all along so what is it telling you they are getting
published afresh.?
Help others by clicking Correct Answer if the question is answered. Found the answer elsewhere? Share it here. "Upvote" is for useful posts.