Follow the instruction here to open the '''Customize Toolbar''' window: https://support.mozilla.org/kb/customize-firefox-controls-buttons-and-toolbars#w_how-do-i-customize-or-rearrange-toolbar-items If the Adblock Plus icon is in the list, you can drag it to your toolbar. If it isn't shown, try going to the '''View''' menu, and clicking on '''Toolbars > Add-on Bar'''. See if the Adblock Plus icon is on the toolbar that appears. (The instructions for dragging the icon to another toolbar are in the article that I linked to.) If the Adblock Plus icon still isn't shown, try re-installing Adblock Plus from https://addons.mozilla.org/firefox/addon/adblock-plus/.

Thanks, problem solved.