Did the Reset feature create an Old Firefox Data folder on your desktop? If so, your extensions would be in there, but unfortunately, they are stored under inscrutable ID numbers instead of their familiar titles, so I can be difficult to identify the one you had before. But an option is to add your old settings folder as a new Firefox profile. You then can run it either to find out what it contains or in lieu of your new one. Possible routes to recovery are described in this thread: [https://support.mozilla.org/en-US/questions/981788 I reset firefox and now some of my add on's are gone and when i try reinstalling them , it says it already exists but i cant find it!!!!]