Home page builder disappeared since gutenberg. How to edit?

Hi,
I am not that tech savvy and yet my tech savvy support person did not seem aware of the new Gutenberg editor when I was horrified to see all my backend editor suddenly change when we did an update! I have reverted back to classic editor for posts for now but what has happened to my homepage template? From the front end it all looks the same – sections, images, sidebar etc, but in the backend it is just a blank page. I need to edit the home page urgently – change some titles link to different categories and so on but there is nothing to edit on the backend. Nobody seems to know why but this must be to do with the Gutenberg thing. Any advise at all please? Thank you.