If you are looking for a topic in the Help Center that you opened, and you don't see it, there are a few reasons why you might not be able to find it:
1. A moderator moved it. Normally, topics are moved in a way that leave a trail or the moderator would send you a private message. However, please see this notice: TiVo Hacking / Replacing Hard Disks and Modems / Problems with Your Upgraded TiVo
2. It may have simply slipped off the first page of topics. In the lower right corner of the topic list, there are links to additional pages of topics and a textbox you can use to search the Help Center for your topic.