Does the button not appear in the menu window? If not, can you still use Autofill from the context menu? One of the screenshots for that extension seems to indicate that that should be available.

Make sure that all toolbars are visible.

• "3-bar" menu button > Customize > Show/Hide Toolbars
• View > Toolbars
  You can tap the Alt key or press F10 to show the Menu Bar
• Right-click empty toolbar area

Open the Customize window and set which toolbar items to display.

• "3-bar" menu button > Customize

• if missing items are in the Customize palette then drag them back from the Customize window on the toolbar
• if you do not see an item on a toolbar and in the Customize palette then click the Restore Defaults button to restore the default toolbar setup

See also:

• https://support.mozilla.org/kb/customize-firefox-controls-buttons-and-toolbars

You can try to reset this pref via the right-click context menu to the default value on the about:config page to reset the toolbar customization.

• browser.uiCustomization.state

You can open the about:config page via the location/address bar. You can accept the warning and click "I'll be careful" to continue.

• http://kb.mozillazine.org/about:config

Thanks. this did help in a way but it's not as easy as before. I used to click on the icon and the date would automatically be entered on website form. Now I have to do extra steps to make that happen but I am able to make it work.

meant to say data in my response, not date.