I know it could sound strange and weird but, if you can get access to your Internet options (through Control Panel or Tools/Options into your browser) and see your proxy settings, specially ‘LAN settings’ > ‘local addresses’.
Also, make sure your browser is not set to “Work Offline” (this option is generally in the File menu). If it doesn’t help, try switching the proxy settings from “Auto-detect” to “No proxy” (I’m assuming you’re not connecting to the Internet via proxy): Left click the avast icon > Settings
Update (Basic) > Details > Proxy
If anything change your proxy settings, you can’t double click, open windows explorer, etc. 