Restarting web server apache2 no listening sockets available

I keep getting the message when issuing a restart on apache2:

Restarting web server apache2

no listening sockets available, shutting down

Unable to open logs

I'm at a loss of what's going on. I've scoured the internet and the best I can seem to find is this:

it means that there is another server already running on port 80 (the default port used for HTTP connections). Only one application can listen for connections in a given port at the same time, so if you have active another server, Apache can't use that port.

The solution for this is as simple as close or disable the other program when you need to use Apache. If you don't know what program is using that port, you can use an utility like Active Ports or TCPView for getting the list of programs associated to any active port in the system.

CAN ANYONE ADVISE OR EVEN TELL ME HOW TO USE THE UTILITIES MENTIONED ABOVE TO FIND OUT WHAT OTHER SERVICE IS USING THE PORT?

Thank you

Stephen