Sometimes it happened that for entire website or for only homepage in Joomla Helix Framework template fontawesome icons are not visible. There is a very simple solution to the issue.
Go to Plugins and search for ytshortcodes.
Make sure that ytshortcodes plugin is there, if not than re-install your template or install ytshortcodes extension
Open ytshortcodes plugin and enable fontawesome. That’s it. Problem solved.