Top navigation banner missing on my theme

Our site lost its banner at the top for the drop downs for communities and categories filtering, view type and “post your event. If you reload the page the top banner will load very briefly and then disappear. So it is there. My site is mycommunitycalendar.ca. I just loaded the latest update and that did not fix it. I did change the theme a few days ago but there have been no problems in support with themes. I do notice that I cannot revert back to my old theme.