On Apache web servers:
service httpd stop
service httpd start
If it didn't solve, run:
/usr/local/psa/admin/sbin/websrvmng -a
On NGINX web servers:
Check 80 port is listening to...
netstat -plnt | grep ':80'
Then,
/usr/local/psa/admin/sbin/nginxmng -d
/usr/local/psa/admin/sbin/nginxmng -e
This will reconfigure all Apache and Nginx web server configuration files, hence set the Apache configuration to ports 7080 and 7081.
If the problem persists afterwards, you must find out, in which file Apache is still binding to port 80. It must then be a custom file that was added, e.g. in /etc/httpd or a subdirectory of that path.