If your internet connection works, but suddenly your browser refuses to get you on-line, reporting connectivity problems, most probably your firewall blocks you.

First disable your firewall and see if you can connect to the internet. Then enable your firewall again, and try again to connect to the internet. Most probably your firewall will now report what is it exactly that hinders internet connection. At least this is how PC Tools Firewall responds.

Usually such a problem is due to some restriction you decided in the past, stopping a program from accessing the internet. Somehow your browser develops a dependence on the process of that program, so that your browser inherits its restriction, becoming itself unable to connect to the internet.

Locate the problematical application in your firewall’s list of application rules, and, if you know and trust this application, give it access to the internet. After you enable internet access for that program, your browser too will be able to connect. If you don’t trust the offending program, uninstall it instead of giving it internet access.