Step through the checklist below to help diagnose the problem.
Turn your modem or gateway off and then back on again. Most Internet connectivity problems are solved by turning your modem off, waiting 15 seconds, and then turning the modem back on. After waiting 45 seconds to allow the modem to synchronize with the server, try reconnecting to the Internet. If your modem doesn't have an on/off switch, unplug the modem from its power source in place of turning it off.
Check your DSL hardware connections. Use the lights on the front panel of your hardware device to verify that it is connected correctly.
Verify that your Network Interface Card (NIC) is functioning properly. If you can't connect to the Internet and the light next to the Data port is off, troubleshoot your NIC.