There are some strange cases when a PC is connected to the internet but will only allow browsing on websites such as Google, Facebook, YouTube, or Wikipedia. This is often the result of updating one's operating system or computer settings. If this is the case, you need to check if your computer's LAN settings have been changed.
Go to the Control Panel > Internet Options > Connections tab and then click on LAN settings:
In the window that opens, clear the checkboxes next to Use a proxy server for your LAN and Use automatic configuration script. The Automatically detect settings option is the only one that should remain enabled:
Click on OK to save your settings. Open your web browser and try to connect to other websites. If the problem persists, then the only alternative left is to perform a system restore.