My router doesnt see the internet

Hello,
I couldnt connect to the internet the otherday.I called comcast they had me unplug router to work on. I was getting a bad ip address.We got that straighted out.Internet works fine when hooked to my laptop.When I go to hook up the router it says not hooked up right (no internet).I know everything is hooked up right .It looks like the router is not seeing the internet.I bought a new router its doing it to both old and new.