Of such an attack, we have already written, but in recent days they have intensified with incredible force. The essence of the attack is that the bots of passwords to the admin panel of the website. It is dangerous not only because the password sooner or later they still can pick up, but the fact that it was created a pretty decent load on the server.
Since the attacks in recent days have purchased just incredible strength, the server hosts many simply can not withstand such loads exorbitant. Hosters naturally try to cope with this scourge, but it is they do not always work, as the number of bots is huge and firewalls can not cope with so many locks. Therefore, some of them, as a temporary solution to block requests for files wp-login.php to wordpress and administrator / index.php for Joomla.
So if you can not get into the admin area of your site, most likely it has banned your hosting provider. Offended by him in this case is not worth it, because firstly he thus protect your site from potential hacking, and secondly leave your site operational, because if he had not done, the server simply could not withstand.
Again, we strongly recommend to hide the administrator panel of your site, to change their address. In wordpress it can be done, for example, by means of a plug Lockdown WP Admin, for example Joomla has kSecure. This will protect their sites from breaking, and also help your hosting provider to cope with the attack.