When you put on or off your site you're changing the state of a varible that you'll find on the variable table called "site_offline". As admin you'll have access on your hosting to the database, look the variable table, search the mentioned variable and change the "1" you'll find to "0". That's all you need to restore you're site, and then you're likely to discover that your admin user has not been deleted Well, at least I hope that you can solve it that way