To unlock an account in Plesk that has been locked out you can use the following steps:

Linux:

How to obtain the Plesk admin password and login to mysql:

  usr/local/psa/mysql/bin/mysql -u admin -p`cat /etc/psa/.psa.shadow` 

Windows:

How to obtain the Plesk admin password and login to mysql:

c:\program files\swsoft\Mysql\bin\mysql -uadmin -P8306 -p 

Linux/Windows:

Switch to psa database:

use psa  

To unlock a Plesk session that is running as user_name, type in:

delete from sessions where login=’user_name’;

To unlock a locked out admin account, type in:

delete from lockout where login = 'user_name';