Enter command line prompt (windows button + R ->cmd or Start -> type cmd in search for programs and files) and then try ipconfig. If you will not be able to reach ipconfig - there is possibility you have some sort of malware in your computer.
If you will reach ipconfig, then type ipconfig /all to check if your DNS is correct. Try nslookup command to see if it will start without error. Also try nslookup to resolve DNS - try
www.google.com.
Also check if internet is working, try pinging exteral IP, for example 74.125.39.104. If you will get request timed out - you have internet problem.
Vaidas Paulauskis