You can check if you have the XML files of the default search engines including Google in the browser\searchplugins folder in the Firefox program folder. If not then you need to reinstall Firefox. You can delete the Firefox program folder to do a clean reinstall. You can find the full version of the current Firefox 36.0.4 release in all languages and for all operating systems here: *https://www.mozilla.org/en-US/firefox/all/ Try to delete the search.json file and possible search-metadata.json and search.sqlite files in the Firefox profile folder to reset the search engines to the default. You can use this button to go to the currently used Firefox profile folder: *Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder) *http://kb.mozillazine.org/Profile_folder_-_Firefox Firefox will rebuild the search.json file from the default search engines in the "browser\searchplugins" folder in the Firefox program folder and the searchplugins folder in the Firefox profile folder. You can check for problems caused by extensions. *https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes ---- Create a new profile as a test to check if your current profile is causing the problem. See "Creating a profile": *https://support.mozilla.org/kb/profile-manager-create-and-remove-firefox-profiles *http://kb.mozillazine.org/Standard_diagnostic_-_Firefox#Profile_issues If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems. *http://kb.mozillazine.org/Transferring_data_to_a_new_profile_-_Firefox