Go to the web site for whoever it is that provides your web hosting, and look for a "contact information", "help", "customer support", "email us", etc. page. This is based on the assumption that somebody there "shut it down" as opposed to you forgetting what the password was, or making a change to the code that broke it, etc. If the latter is the case, then you will have to either go into the database create/change your login, or some other solution which none of us can fix for you with our magic wands in spite of being totally ignorant as to what the root cause of your problem is.
