launchctl: is shown because
apachectl is using
launchd's control script,
launchctl, to start and stop Apache.
Error unloading means the given daemon/service of
launchd can not be stopped. This usually happens if the given daemon is already stopped.
org.apache.httpd is the name of the plist file defining how httpd is run by
launchd. If you are curious the actual plist is at
If the server is merely off just use:
sudo apachectl start
to get it running again.
Otherwise I would check system.log (you can use Console.app) and see if there are any, more informative, error messages.