ERROR 1045 (28000): Access denied for user ‘root’@'localhost’ (using password: NO)

While trying to use mysql in plesk I am getting the following error :
ERROR 1045 (28000): Access denied for user ‘root’@'localhost’ (using password: NO)
ERROR 1045 (28000): Access denied for user ‘root’@'localhost’ (using password: YES)
Solution :
echo “use psa; truncate lockout;” | mysql -u root -p`cat /etc/psa/.psa.shadow`