If a thread has been deleted, can I still find it someplace?
Yes. Threads that are deleted from MetaFilter, MetaTalk or AskMetaFilter still show up at their old URLs with the reasons for deletion written in, but they no longer show up any other place on the site. They are also closed to new comments. In extremely unusual instances a thread will be removed with no trace.
If your post was deleted, check your Mefi Mail. If you received a Mefi Mail automatic reminder message when your post went up, that message will have the URL of your post. Go to that URL and you will be able to see the post and a brief note about why it was deleted.