Ok, either your NIC or your router is not setup for DHCP or the NIC has been disabled.
Is the appropriate LAN light still lit? (1-4)
If so,
I suggest performing a factory reset of the router by pressing and
holding the reset button until the test light illuminates. Release the
button and wait until the router reboots. Try the ipconfig again.
You will lose your router AOL settings.
If not
Post back.