You could try rebuilding that forum's posts, they may re-appear. If they were deleted tho, they may just be gone. You could try the search indexes for that forum, but if it's been 2 years, it's possible that search indexes have been updated and removed references to old deleted posts.
You could also try the wayback machine through the internet archive, it's possible those topics have been indexed. Google may also have a copy in their cache.
