You can download the English version from http://www.mozilla.com/en-US/firefox/all.html Run the Firefox setup file and install it on top of your current version of Firefox. You may need to change a setting afterwards. # Type '''about:config''' into the location bar and press enter # Accept the warning message that appears, you will be taken to a list of preferences # Locate the preference '''general.useragent.locale''', it should be set to either '''en-US''' or '''en-GB''' depending on which English version you installed. If it is not set to that, double-click on the setting to change its value.