To change the port search for the next lines in the httpd.conf file (click on the WAMP tray icon then Apache --> httpd.conf
Listen 80
and
localhost:80
and change the port number to something else. That is also the port you need to add to the firewall exception in Windows and the one you need to forward in your router.
Personally I wouldn't recommend to change WAMP's settings, since I believe this is more a problem with either your router or your ISP, I would recommend you to call to your ISP and ask for assistance on how to forward a port in your router/modem.
You can also check if a port is open in
http://canyouseeme.org, I suggest you to do this before anything else.