What is your home page suppose to be?

Type about:preferences#general<enter> in the address bar.

There are two settings;

• When Firefox Starts

When the browser is started, what do you want to display. Many of us choose Show My Home Page.

• Home Page

When a new page is opened, what do you want displayed.

1. Use Current Page. Use what ever page(s) are open at that time.
2. Use Bookmark
3. Restore To Default. about:home shows a Mozilla home page with tools.

You can use any of these that you wish;

about:home (Firefox default home page), about:newtab (shows the sites most visited), about:blank (a blank page),

or you can enter any web page or about: page you want.

I understand that. But the actual screen is blank - as in I can't type in a web address or search for anything. My screen is blank.

Ahh. I thought you were talking about about:blank

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

Start your Computer in safe mode with networking. Then start Firefox. Try Safe web sites. Is the problem still there?

Starting The Computer In Safe Mode;
Free Online Encyclopedia

thank you - I called Apple and they helped me solve it. I removed a few files and restarted my computer which seems to have done the trick.

Good to hear. For others with the same problem, please post what you did. Then flag that post as Solved Problem.