Similar thing is happening to me now. I got home from the gym and the internet wasnt working... all green lights on modem, even checked the page for its status and said everything was up and running but no packets were being sent or received its really ****ing me off.. this is the third time its happened to me. the modem is about 2 yrs old i try resetting it and everything, reboot, reconnect check plugs and connection, refresh but nothing. now mysteriously it starts working again on and off. Im going to change ISP as soon as possible! ... Your not with Telstra by any chance are you?
EDIT - Ive contacted my ISP about it before and they had no solution after waiting 20 minutes on the phone to get through to someone, now I cant get through at all.. Telstra provide a poor service and even worse customer service.