Do you still see the default search engines in the searchplugins folder in the Firefox program folder (C:\Program Files\Mozilla Firefox\)? If not then you need to reinstall Firefox. You can find the latest Firefox release in all languages and for all Operating Systems here: *Firefox 15.0.x: http://www.mozilla.org/en-US/firefox/all.html Your bookmarks and other profile data are stored in the Firefox Profile Folder and won't be affected by an uninstall and (re)install, but make sure that "remove personal data" is NOT selected whenever you uninstall Firefox. *http://kb.mozillazine.org/Profile_folder_-_Firefox ---- Try to delete search.json file and a possible search.sqlite file in the Firefox Profile Folder. *http://kb.mozillazine.org/Profile_folder_-_Firefox You can use this button to go to the Firefox profile folder: *Help > Troubleshooting Information > Profile Directory: Show Folder