If your internet is not working the first thing to try is turning off your router for at least 15 minutes. This can clear a lot of faults and check to see if it is a simple problem.
After you have turned off your router and it is still not working see if the telephone line is working or has a lot of noise. If there is a problem with the telephone it is probably that that is causing the problem.
If the line is clear and the router has been restarted it is worth logging on to the router sometime there can be errors on the router its self which will be displayed when logging on or even sometimes it can be a communication issue between the router and the computer. We have a FAQ explaining how to logon to your router.
If all this has failed then it is time to start phoning your service provider or your I.T. support company.