I checked with our web guy and he assures me that nothing has been deleted by us. The web site was compromised once in the early years and some very early posts were lost but this was long ago. I did find that the default setting for replies was 100 so I had it raised to 500 which should help. I also did some searches and found the same posts and a few others depending on specific wording. They are there but some times the wording in the posts affects the search.
Again all post are there to the best of our knowledge