Suddenly Mozila Firefox does not open in Windows 10 PRO

I had Mozila Firefox installed ina Windows 10 Pro platform and worked ok.  Suddenly, it stopped openning.   I uninstalled it and downloaded Mozila Firefox 64bits ver 57, reinstalled it and when I click on the icon nothing happens.  I went to Task Manager and I waw that Firefox is running in backgroud mode.   I have searched for solution and only found one suggestion that I have not tried which is to uninstall Norton and install it competitor.

I am a Norton customer since 1986 when Norton Utilities was the best tool to have.   What shoud I do?