Take a look in Control Panel>Internet Options>Connection tab>LAN button and tick "Automticaly detect settings", click Apply and OK your way out.
If you had a Proxy setting that will overarch it. If that was the case, run your anti-virus scanner.
If taht doesn't do the trick, open a Command Prompt - Windows key and R together then type cmd and hit Enter. At the prompt type
netsh winsock reset catalog
and press Enter. Restart the machine and see if that fixed it.