PS: While I stand by all that I've written above, I still can't see what it's got to do with problems with Firefox!
If you're having problems with Firefox, my recommendation is as follows:
1. Make a note the names of any extensions that you're using and you wish to keep. (Three lines > Add-ons and themes > Extensions);
2. Then go to . . .
Three lines > Help > More Troubleshooting Information
and click on 'Refresh Firefox' (top right).
That will set Firefox back to its 'fresh out of the box state' but still while retaining all of your bookmarks and most of your personal settings. However it will remove any extensions that you've got.
3. Reinstall any extensions that you want back and reset any personal preferences, such as your Home Page, which were lost during the reset.
Also be aware that some extensions can cause problems with Firefox. So it might be best to re-install any extensions you use one at a time, so that you can identify anything that's causing problems.