But let's see... You're using the Internet wireless or cabled? If the first, tried to hook it up to a cable? Check the settings in your router, sometimes they end up being put back to manufacturer settings.
Check all cables, check what the lights on your router do, if they shine/blink like they always do, call your Internet provider to sort it out, you know, those sort of things
It sounds like you're wireless. Log in to the router and change the channel and networkname (SSID). You'll have to find your network again and connect to it again but it might work.
