How to Reset Mozilla Firefox
If your Mozilla Firefox Web browser suddenly has an unwanted toolbar, its home page has changed without your permission or your search results appear in a search engine you never chose, it may be time to reach for the browser reset button.
Many legitimate pieces of software, especially freeware, slap on third-party, browser-hijacking extensions when you install them. The easiest fix is a full browser reset.
Resetting Firefox will probably not delete bookmarks, or saved passwords, but there are no guarantees. It might be best to back up your Firefox bookmarks first. The steps below are identical for the Windows, Mac and Linux versions of Firefox.
1. Click the icon that looks like three stacked lines at the top right of the browser window.
2. Select the question-mark icon at the bottom of the drop-down menu.
3. Select 'Troubleshooting information' in the slide-out menu.
4. Select the 'Reset Firefox' button at the top right of the new Web page.
5. Select 'Reset Firefox'in the confirmation pop-up window.