How can I unblock my Hotmail account?

As I go to sign in my Hotmail account, it tells me that it has been blocked. I recently tried to notify Microsoft of a hacking issue that I think may have led to this problem, they gave me a PIN but I can't find where I put it. I really need to access this account as it is my main account that I use for the majority of important stuff- namely my University applications etc. Does anyone know how this can be resolved without the PIN? Any useful suggestions welcome!