Cant get on the internet,please help!!

Hello,
Hi all, yesterday i was on my computer fine.. I go out for a couple hours and come back to the internet not working at all. I checked my modem i have all the lights required.. So basically i have internet connection but nothing will connect to the internet on my computer. I checked if i have a signal on the computer and it says im connected. Everytime i open a browser (ie or google chrome) i get a server not found. Not only my computer, but my laptop xbox360 and ps3 cant connect to the internet.. I dont get it, i have internet but i dont? Doesbt make sense to me.. Please help!