Hi, Please try this: '''Help''' ('''Alt''' + '''H''') > '''Troubleshooting Information''' and '''Open Containing Folder''' (this opens your [http://kb.mozillazine.org/Profile_folder_-_Firefox Profile Folder & Files])and exit Firefox. Delete the extensions.ini and '''extensions.sqlite ''' files in the folder and start Firefox. Re-enable the add-ons if necessary. ............................................................................................................................... Useful links: [https://support.mozilla.com/en-US/kb/Options%20window All about Tools > Options] [http://kb.mozillazine.org/About:config Going beyond Tools > Options - about:config] [http://kb.mozillazine.org/About:config_entries about:config Entries] [https://support.mozilla.com/en-US/kb/Page%20Info%20window Page Info] Tools (Alt + T) > Page Info, Right-click > View Page Info [https://support.mozilla.com/en-US/kb/Keyboard%20shortcuts Keyboard Shortcuts] [https://support.mozilla.com/en-US/kb/Viewing%20video%20in%20Firefox%20without%20a%20plugin Viewing Video without Plugins] [http://kb.mozillazine.org/Profile_folder_-_Firefox Firefox Profile Folder & Files] [https://developer.mozilla.org/en/Command_Line_Options#Browser Firefox Commands] [https://support.mozilla.com/en-US/kb/Basic%20Troubleshooting Basic Troubleshooting] [https://support.mozilla.com/en-US/kb/common-questions-after-upgrading-firefox-36 After Upgrading] [https://support.mozilla.com/en-US/kb/Safe%20Mode Safe Mode] [http://kb.mozillazine.org/Problematic_extensions Problematic Extensions] [https://support.mozilla.com/en-US/kb/Troubleshooting%20extensions%20and%20themes Troubleshooting Extensions and Themes] [https://support.mozilla.com/en-US/kb/Troubleshooting%20plugins Troubleshooting Plugins] [http://kb.mozillazine.org/Testing_plugins Testing Plugins]

I delete .mozilla folder and re-install addons.But it's still disabled all addons.What is this problem?

You may have to make sure that Firefox is completely exited before deleting. Also, make sure that Firefox is starting normally. Please also see [https://support.mozilla.com/en-US/kb/Firefox%20is%20stuck%20in%20Safe%20Mode this] and [https://support.mozilla.com/en-US/kb/Safe%20Mode?s=safe+mode&r=0&as=s this.]