Is there any reason a thread would just disappear? it hasn't been moved or locked or anything, it is just gone from the board altogether. This has happened to me twice. I even did a search for all posts I have written on and it isn't there either.
A rule may have been broken by the originator of the thread or after you posted.
If it applied to you, you would have been banned as notice to email me, or your post would have been "soft" deleted with a message why it was deleted. So the deletion affected you but was not caused by you.
Read and follow the updated Posting Policy.