You can’t login to your own site… That might feel scary, but first of all, don’t panic!
I recently experienced that issue with my own site, and I wanted to find out what was the root of the problem. There are several reasons, what might affect your login page, but let’s not forget the issue might be caused by your newly installed plugins or themes.
Even if your login page doesn’t work at the moment, you can still reach your site from your server. You might have cPanel, FTP, or access by the terminal.
My problem was caused by a security plugin, called WP Cerber, which by the way does the job, and protects my site from brutal force attacks, and logins from not authorized parties.
It turned out that my IP got blocked after 2 attempts of the wrong password (It happens sometimes).
In case you have the same issue, there are some ways to fix the problem. My fastest bet would be to use a VPN service. Betternet actually offers that for free. I use their Chrome extension and their app for my iPhone, it comes handy when you’re in China and would like to reach your Gmail, and other blocked sites, or apps. After login into your WordPress site, check the plugin’s settings and remove the block from your IP address. Tip: add your IP to the whitelist, then it’ll never be blocked again in the future.
The other way to fixing the issue is by manually logging into (SSH) the server and MySQL database, then find and delete the row that has your IP address in it. An easy way to find out your IP, check out this website!
Keep your site always secure, Happy New Year!