click start
then run
type cmd
click ok or enter
type ipconfig/release
>>wait a minute
type ipconfig/renew
/// also in the run box
type sysdm.cpl
enter or ok
hardware tab
then device manager
do you see any " X" or " ! "
or uninstalled devices, specifically see if your network card is in devices
go back to the first step
type ipconfig/all
post your ip and gateway address
...if you have cable turn off the cable modem, and the pc, turn the cable modem on wait for it to train, then turn on your pc.
after you get this issue fixed you really need a router or a firewall to protect you from the internet,,, a router is best and they are cheap.