try the following:
start cmd.exe as an admin (windows key +x then press A)
ipconfig.exe /release
ipconfig.exe /renew
now you can see if you have network connectivity restored.
otherwise you need to make sure you have network access to a router that is working. if it is your own router and cable modem you should power down the router, then power down the cable modem, disconnect the cable modem main cable. wait 1 min and reconnect the cable modem cable, power on the cable modem, wait 1 min, then power on the router. Now repeat the above commands on your PC and see if you get a good connection.
(assuming you are attempting to connect to the correct router)
Ekliberty :
I need help. My pc has been working for with ethernet and I did not...