If you cannot connect to the Internet, your Internet Protocol or TCP/IP may have been corrupted, and you may have to reset TCP/IP. TCP/IP is one of the core components required by your Windows computer to connect successfully to the Internet. In such a situation, even though you may be physically connected to the Internet, packets do not get transferred over the network and you may see the “The page cannot be displayed” message when you try to connect to a URL.
If your Windows 7 computer is unable to connect to the Internet, you may want to reset TCP/IP. Do remember to create a system restore point first.
Reset TCP/IP using NetShell utility
You can reset Reset Internet Protocol to its default state using the NetShell or netsh utility.
To do so, open command prompt, type the following and hit Enter:
netsh int ip reset resettcpip.txt
When you run the command, TCP/IP is reset and the actions taken are recorded in the log file, created in the current directory, named here as resettcpip.txt.
Reset Internet Protocol using Fix It
You can take the easy way out. Use this Microsoft Fix It 50199 to easily and automatically reset Internet Protocol.
Do note that the Fix It works on Windows 7 and Windows Vista, and may not work on Windows 8.
How to fix Network & Internet connection problems in Windows and how to reset Winsock in Windows 7 may also interest you.