theme breaks site

I have been using this theme for the last two weeks without any problems. Today my site shows as a blank white page, only with this theme.
If I activate any other theme, the site works perfectly.
Can you advise me please.

I have contacted my website hosting company and they have said:

"Looks lie a coding issue, here's the error I'm getting in the logs:

PHP Fatal error: Function name must be a string in
.... ....... .....wp-content/themes/ShopAndBuy/gavern/helpers/helpers.layout.php on line 837"


Line 837 code is this:

$conditional_result = $conditional_function();

Perhaps someone can help with this?

My site works with all other themes.

Hello,

Could you please provide me with the backend and FTP access to your website via PM (click the “Private Message” text underneath my avatar) so that I may analyze it?

Thank you. I have fixed it now.