|if the protocol is lost, your Windows installation may need to be repaired, but check this first.|
Open Control Panel, Network Connections. One of the connections is your method of connection (if you plug into an ethernet cable, it's probably "Local Area Connection," and if it's wireless it's probably called "Wireless Connection" or something like that).
Right click on your connection and click Properties.
it should say "Connect Using:" at the top of the window, and the name of your Network Interface Card (NIC) should be shown. If it is not, open the Device Manager (right click My Computer, Manage) and verify that your NIC is showing up under the "Network Adapter" category in the Device Manager. If it's not, or if there's a yellow triangle on the device, you need to reinstall network card drivers.
Back to the "Local Area/Wireless Connection Properties" window: Click on "Internet Protocol (TCP/IT)" It should have a check in the box next to it. If this is not displayed, but your NIC is showing up fine in Device Manager, your OS needs to be repaired. If this is displayed (your post indicates that it IS there), highlight it with a click and then click Properties. On the General tab, both radio buttons should be set to "Obtain...automatically."
btw, do you run Antivirus and are your definitions up to date?