how to reset firefox

At the top of the Firefox window, click the Firefox button, go over to the Help sub-menu
and select Troubleshooting Information.



Click the Reset Firefox… button in the upper-right corner of the Troubleshooting Information page.
To continue,
1. click Reset Firefox in the confirmation window that opens.

1. Firefox will close and be reset. When it's done, a window will list the information that was imported. Click Finish and Firefox will open.