Check to see if it is hiding on a hidden toolbar or most likely in the Customize window.

Right-click a toolbar and select Customize.. and if there then just drag and drop it to where you want it and then [Done].

You can find the toolbar Home button at the far right end of the Navigation Toolbar.

You can drag the Home button from its current position at the right to the previous position at the left of the location bar if you do not like that new position.

• http://kb.mozillazine.org/Toolbar_customization

This could also help re the position and combination of buttons etc -

http://www.mozilla.com/en-US/firefox/features/