after changing database credentials i'm facing this error

Warning: mysqli::__construct(): (HY000/2002): Connection timed out in /var/www/vhosts/tbdeel.net/httpdocs/system/library/db/mysqli.php on line 7
Fatal error: Uncaught Error: mysqli object is already closed in /var/www/vhosts/tbdeel.net/httpdocs/system/library/db/mysqli.php:10 Stack trace: #0 /var/www/vhosts/tbdeel.net/httpdocs/storage/modification/system/library/db.php(36): DB\MySQLi->__construct() #1 /var/www/vhosts/tbdeel.net/httpdocs/system/framework.php(80): DB->__construct() #2 /var/www/vhosts/tbdeel.net/httpdocs/system/startup.php(104): require_once('...') #3 /var/www/vhosts/tbdeel.net/httpdocs/index.php(20): start() #4 {main} thrown in /var/www/vhosts/tbdeel.net/httpdocs/system/library/db/mysqli.php on line 10

Kindly help me to solve this am really stack
this is my website link : tbdeel.net

This means your MySQL server timed out. This isn't an OpenCart issue, but a hosting issue. Contact your web host and ask them to increase the MySQL memory/timeout limits.