If you are hard-wired into an Ethernet port, and you are not detecting the network, I would suggest making sure your Network Drivers are up to par.
Do this by going to Start > Device Manager, and find your Network Drivers. Then update them. After that and once you are successfully connected to the Internet, Windows Updates help keep the rest of drivers up to par as well as key Windows components.
This will also solve your Wireless Internet issues, if you have a Wireless card.