Try one of these articles:
- Reset Firefox – easily fix most problems Fix slowness, crashing, unwanted toolbars, search hijacking and more by restoring Firefox to default settings. We'll save your bookmarks, tabs and passwords.
- Uninstall Firefox from your computer This article describes how to remove the Firefox application from your computer and also how to remove the personal information that Firefox stores.
- Reset your Master Password if you've forgotten it You can reset your Firefox master password if you've forgotten it, however, this will remove all of your saved usernames and passwords. Learn how to do it.
- Stop Firefox from opening multiple tabs when it starts A pipe character in the address of a home page can cause unexpected results when Firefox opens. This article explains how to fix that.