Sometimes you may find that a topic you've created, posted in or have been following doesn't appear in the forum any more. In these cases, it's highly likely that it's been moved to a different forum that's more in keeping with the general organization of this site.
The vast majority of these topic moves are to the Troubleshooting forum here: http://zevo.getgreenbytes.com/forum/viewforum.php?f=7
Check there first, and if you still don't see the topic, try searching for it here: http://zevo.getgreenbytes.com/forum/search.php
If it truly seems to be gone, please drop the admins an email.