Error establishing a database connection

Open wp-config.php and make sure that the following entries are corrrect:

• Database name
• Database username
• Database password
• Database server

define( 'DB_NAME', 'database_name_here' );
/** MySQL database username */
define( 'DB_USER', 'username_here' );
/** MySQL database password */
define( 'DB_PASSWORD', 'password_here' );
/** MySQL hostname */
define( 'DB_HOST', 'localhost' );