What do you mean by "older" ?
The forum changed to new software about 2 years ago (give or take a few months, I don't rememer the exact date) and I don't think much (if anything) from the old forum was carried forward
Have you used the new & improved forum search function to find specific topics?
Yes, much was lost forever, when Adobe went to "Jive City." However, before that, there was also a major change to the previous forums, and though attempts were made to archive some older posts, most were lost, in one way, or another. IIRC, that was ~ 18 - 24 mos. before Jive. Much was just flat lost, and that which was archived, was of little use, as all titles were replaced by a string of about 16 numbers. Also forums got combined, so if one went to the archive, they had to open every thread, and look at it, to even know which forum that it came from, much less what it was about. Not as bad as the burning of the Great Library at Alexandria, but a lot of great material was lost forever. Even most of the FAQ's needed to be rewritten.
Going back, as John T. says, about two years, the posts are still here - before that, I'd say slim chance.