192.168.1.1 click this and use username admin : pass admin
this should take you to your routers setting's page, where it say's wan connection type, set it to obtain ip automatically.
then at the top of the page click on the status tab, if there's no public ip address in the wan part or if it just say's 0.0.0.0 unplug the modem and wait until it fully reboot's then get a small object small enough to fit in the reset hole on the front of the router, push it for about 5sec's and log back into the router,
check the status page of the router to see if you have a public address
should work after this, if not i don't know what to suggest