To clarify: tried to enter new Google font and have lost whole site

Apologies … but I realised that the earlier thread didn’t really make clear the nature of the issue. At present, I can only get any page (including dashboard) if I use the back arrow: any attempt to enter a URL or follow a link gets a blank or server error. If I let the computer go to sleep, I’m concerned I’ll lose everything and have no way of fixing it. But it’s 3 AM (which may be why the mistake happened in the first place), so I’m a bit worried about falling asleep. Hope someone will see this. So sorry for bother.

I went to this thread: https://kriesi.at/support/topic/new-custom-font/ and tried to follow the instructions to enter the Slabo font.
It worked and I got Slabo in the drop-down box, but when I selected it, the site defaulted to Arial.

I wondered whether I should also have followed the first part of the instructions and so added them to functions.php. Nothing changed, so I deleted them. But then I lost the whole site – and I am wondering if I deleted something else in the process without noticing.

The functions.php page now ends:

/*
* register custom functions that are not related to the framework but necessary for the theme to run
*/

require_once( ‘functions-enfold.php’);

/*
* add option to edit elements via css class
*/
// add_theme_support(‘avia_template_builder_custom_css’);

Have I deleted something that I should not?