Sounds a bit strange to me. Why are they prohibiting the use of SEO?
I honestly don't know what you can do to retrieve your posts if they have shut it down and closed your account. If you cannot get acces to it you cannot transfer it either.
I do not why they are prohibiting SEO. But, I do not recall doing anything to go against the terms and conditions. One minute, my blog was up and another, it was down. I contacted their admin to ask for explanation, etc but, no response to date. I found about the new policy through another source. That seems to be the only explanation.
BTW, I am referring to the free version of Wordpress...