Is Firefox installed? You can find the latest Firefox release in all languages and for all Operating Systems here: *Firefox 16.0.x: http://www.mozilla.org/en-US/firefox/all.html Download and save the Firefox installer to the desktop and start the installation with a double-click on the desktop icon. ---- If you can't open Firefox then see: *http://kb.mozillazine.org/Browser_will_not_start_up A possible cause is security software (firewall,anti-virus) that blocks or restricts Firefox or the plugin-container process without informing you, possibly after detecting changes (update) to the Firefox program. Remove all rules for Firefox and the plugin-container from the permissions list in the firewall and let your firewall ask again for permission to get full unrestricted access to internet for Firefox and the plugin-container process and the updater process. See: *https://support.mozilla.org/kb/Server+not+found *https://support.mozilla.org/kb/Firewalls