If you cannot connect to the Internet and you have an ADSL connection it can be the modem – they do not last forever.
Some modems are a security risk which can transmit your data without you knowing.
Click this link to the right to test the security of your router: TEST YOUR ROUTER.
Look at the lights on the modem , there is an ADSL light on there ( Phone Symbol ) , no light , no phone line , no internet
Know your login to the internet which comes from your isp and your password as you may have to logon to the router.
Be aware that most ISPs other than Telstra will not be able to test your phone line and this can take up to 48 hours
Make sure you have security on your modem for wifi – Routers And Security
Change the login for your router from the default – most people never do this
Learn how to login to your router and check for updates
Be aware that some ISPs will attempt to charge you to send someone out to diagnose your internet connections