When you start Firefox back up again, it should explore your profile folder, other folders, and the Windows registry to rebuild the list. extensions.sqlite to something like extensions-old.sqlite (might not exist depending on how long you've been using this settings folder).extensions.json to something like extensions-old.json.extensions.ini to something like extensions-old.ini.compatibility.ini to something like compatibility-old.ini.Pause while Firefox finishes its cleanup, then rename any of these files that you find: Leaving that window open, switch back to Firefox and Exit, either: This should launch a new window listing various files and folders in Windows Explorer. In the first table on the page, click the 'Show Folder' button.
type or paste about:support in the address bar and press Enter.(menu bar) Help > Troubleshooting Information.'3-bar' menu button > '?' button > Troubleshooting Information.Open your current Firefox settings (AKA Firefox profile) folder using either It's possible that an extensions-related settings file has become corrupted. If you haven't already shut down and restarted Windows, you might try that in case this is a file permissions problem that sometimes occurs after Windows updates.
