If they are gone because the toolbars are hidden (item #2,4,6) or because the extensions are disabled (item #15).

Use "Alt" to see the Menu bar then View menu > Toolbars unhide the hidden toolbars. Menu bar is mutually exclusive to the menu bar.

For more details read about the changes and what you can do to make Firefox better for you. ...

You can make Firefox 6.0 look like Firefox 3.6.*, see numbered items 1-10 in the following topic Fix Firefox 4.0 toolbar user interface, problems (Make Firefox 4.0 thru 6.0, look like 3.6). Whether or not you make changes, you should be aware of what has changed and what you have to do to use changed or missing features.

• http://dmcritchie.mvps.org/firefox/firefox-problems.htm#fx4interface

Check that the Bookmarks Toolbar is visible and that the "Bookmarks Toolbar items" is still placed on the Bookmarks Toolbar.
If the menu bar is hidden then press F10 or hold down the Alt key, that should make the "Menu Bar" appear.

Make sure that toolbars like the "Navigation Toolbar" and the "Bookmarks Toolbar" are visible: "View > Toolbars"

• Open the Customize window via "View > Toolbars > Customize" or via "Firefox > Options > Toolbar Layout" and check that the "Bookmarks Toolbar items" is on the Bookmarks Toolbar
• If the "Bookmarks Toolbar items" is not on the Bookmarks Toolbar then drag it back from the toolbar palette in the customize window to the Bookmarks Toolbar
• If you do not see the "Bookmarks Toolbar items" or other items that are missing in the toolbar palette or on a toolbar then click the "Restore Default Set" button

• http://kb.mozillazine.org/Toolbar_customization
• https://support.mozilla.com/kb/Back+and+forward+or+other+toolbar+items+are+missing