Like Scottray said, test the cables. It's the single easiest thing to test and confirm if it's working or not. Cat6 is more of a hassle to cable than Cat5(e) despite using the same wiring setup. It's very easy to not push a wire far enough in to the cable end. I've been wiring this stuff for 20 years and Cat6 took a more concentrated effort to ensure proper wiring.
Once you know your wires are sound, you can start diagnosing the rest of your network, which typically is more time consuming than a wire test.
After you confirm if the wires are good, then look at your router/switch setup. Isolate it off your Internets Modem (assuming it's not an all in one unit). Ensure the problem is local to it and not an internet. If that's working, then start looking at your Modem and it's wiring and possibly contact your ISP if there is an internet issue at play.