Legatus said

Hello, After firefox update v42.0 i can't access again my options menu.When i press options firefox opens just a blank tab.About:config solution doesn't work anymore.So i'm open to suggestions...

Legatus, Have you tried uninstalling and reinstalling Mozilla Firefox? This will usually fix most issues. If the issue still persists after this we can at least determine it is a settings or compatibility issue.

Respectfully, cpeters008

So bookmarks and passwords won't be deleted right?

Firefox comes in two or more folders on all computers. They are;

Maintenance: (Programs Folder) <Windows Only> Firefox itself: (Programs Folder) And one folder in the profile of each user on the computer.

If you remove the Firefox folder, the user folders would not be affected.

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options) key, and then starting Firefox. Is the problem still there?

So Clean Reinstall worked for me thanks.