You're
posts appear to still be there.
The "new posts" link at the top of the forum will only show you the new posts/threads that you haven't read since your last visit. If you personally create a new thread, or post in an existing thread, the system assumes you viewed it and they will not show up on "new posts" for you again until someone else replies to the thread. However, they will show up for everyone else that hasn't viewed that thread.