After you post a question on Letsdiskuss.com, it goes for review by the admin. If the question you posted is not showing on your profile, the chances are that it has been deleted by the admin due to some reason.
Admin usually deletes a post only when it is reported, and if your post is reported, you will receive a notification and hence will be informed that your post is going to be deleted.
If you have not received any notification and the post or question is not showing in your profile, this means that it is neither approved nor deleted. This implies that the post has not yet been reviewed.