Is the PC Link light solid?

    Yes

If NO then check all your connections, turn off your PC, turn off the cable modem and turn everything back on.

Check list:

1. Your PC is not turn on; turn it on.
2. Your  Ethernet ( or CAT-5) cord is not plugged into the cable modem; plug it in.
3. Your network card is bad; replace it.
4. The cable modem Ethernet port is bad; contact support to swap it out.