Some malware will intercept all of your internet traffic by setting up a proxy in your internet settings. After removing the malware, your browsers will stop working and show "Proxy error" messages. You can go to your internet settings to remove the malware proxy, or just use this batch file to do it for you.

INSTRUCTIONS:
Download this batch file to your desktop. Then, right-click it and select "Run as Administrator". Reboot your PC.

If your browser is still broken, then it means your internet might be failing in some other way or you might still have malware on your machine.