Hi,
Have you tried logging in via SSH and rebooting? Or restarting apache?
/etc/init.d/zentyal apache restart
I'm not sure whether Zentyal writes over this config file or not but have a look at /etc/apache2/ports.conf. Maybe edit it back to 443 and try restarting apache or rebooting Zentyal. Mine looks like this:
# If you just change the port or add more ports here, you will likely also
# have to change the VirtualHost statement in
# /etc/apache2/sites-enabled/000-default
# This is also true if you have upgraded from before 2.2.9-3 (i.e. from
# Debian etch). See /usr/share/doc/apache2.2-common/NEWS.Debian.gz and
# README.Debian.gz
NameVirtualHost *:80
Listen 80
<IfModule mod_ssl.c>
# If you add NameVirtualHost *:443 here, you will also have to change
# the VirtualHost statement in /etc/apache2/sites-available/default-ssl
# to <VirtualHost *:443>
# Server Name Indication for SSL named virtual hosts is currently not
# supported by MSIE on Windows XP.
Listen 443
</IfModule>
<IfModule mod_gnutls.c>
Listen 443
</IfModule>
Hope this helps.
Cheers,
Andy