Firefox is a great web browser but sometimes things go wrong and you may want to reset your web browser to its original state. This could be because of unexplained slowness, malfunctioning extensions or simply a desire to refresh your browser. Instead of uninstalling and reinstalling the browser you can conveniently Reset Firefox.
To Reset Firefox open the Firefox menu then from the Help menu select Troubleshooting Information. In the top right of the tab that opens is a button with the option to reset Firefox. On Windows you can also access this option when Firefox is not running through the Start Menu by selecting your Mozilla Firefox folder in All Programs and running Mozilla Firefox (Safe mode). In the dialog box that opens you will be presented with the option to reset Firefox.
When you reset Firefox you will be clearing, cookies, bookmarks, browsing history and saved passwords. You will also lose any extensions (add-ons) that you manually installed. Since these may be the origin of the problems that caused you to reset the browser in the first place this behaviour is understandable. You can always install Firefox Add-ons after the reset is complete.