Sometimes you may not able to access plesk control panel ,so try to access it via RDP and even if you are not able to login to plesk .Then Simply follow one of the following solutions
Solutions :
a)Restart your system
b)Restart Plesk control panel and Plesk Management Service on Plesk icon via RDP
If above solutions did n’t solve your problem contact your support.
Do you get these errors When you try to access your Plesk control panel?
ERROR: PleskMainDBException [MySQL][ODBC 3.51 Driver]Can’t connect to MySQL server on ‘localhost’ (10061)
0: C:\Program Files\SWsoft\Plesk\admin\plib\common_func.php3:608 reconnect()1.: C:\Program Files\SWsoft\Plesk\admin\plib\common_func.php3:590db_connect()
2: C:\Program Files\SWsoft\Plesk\admin\auto_prepend\auth.php3:63
Solution:
Just Restart/Reboot your Server.If the problem persists even after that then contact your support!