What's your computer system and Firefox version?

Start Firefox in Safe Mode {web Link} by holding down the <Shift>
(Mac=Options) key, and then starting Firefox. A small dialog should appear. Click Start In Safe Mode (not Refresh).

Is the problem still there?

I'm using windows 10 when I open fire fox all I get is the blue circle of death that spins and spins, nothing else happens.

Did you try launching Firefox directly into the Firefox Safe Mode, as Fred suggested?

On Windows devices hold down the Shift key when opening Firefox. https://support.mozilla.org/en-US/kb/troubleshoot-firefox-issues-using-safe-mode