my last pass extension has disappeared from the toolbar and I cannot get it back - how do I restore it?

Is your LastPass extension in your extension list? Click on the puzzle piece icon on the toolbar, is it there? What about if you then click on "Manage extensions"? If LastPass is in the "Disabled" category, toggle the associated slider to reenable it. If LastPass isn't in the page at all, you may have to reinstall it at https://addons.mozilla.org/en-US/firefox/addon/lastpass-password-manager/