Oftentimes, WordPress hosting companies recommend to install a plugin like Limit Login Attempts. Although a nifty tool, sometimes Limit Login Attempts can be an annoyance as it can lock you out too if you entered a wrong password a few times.
The easiest solution is to delete Limit Login Attempts using FTP then re-install it later once you can login.
For advanced users who are familiar with MySQL and PHPMyAdmin, you can unblock limit login attempts using the following SQL query:
UPDATE wp_options SET option_value = ” WHERE option_name = ‘limit_login_lockouts’ LIMIT 1;
If you want to unblock specific ID, run this query:
UPDATE wp_options SET option_value = REPLACE(option_value, ‘18.104.22.168’, ”) WHERE option_name = ‘limit_login_lockouts’ LIMIT 1;
Read the rest of the post here: http://www.wpbeginner.com/wp-tutorials/how-to-unblock-limit-login-attempts-in-wordpress/