When I try to go to google, it says the proxy server is refusing connections. I do go to the Firefox button, click on Help, go to Troubleshooting Information, click on Reset Firefox, but it doesn't work still. I also can't go on Internet Explorer and Google Chrome.
You should also try windows safe mode with networking by tapping F8 when booting on your computer. If this is successful, you should check your Firewall, anti-virus, and scan for Malware and a Possible Rootkit.