NO ACCESS to Add listing / Edit listing pades

I cannot open my add listing and edit listing pages, a page is loading where it says: “add new listing” and there is the featured image but without the content. Maybe there is no link to the templates? I think it happened after I created my child theme but the other pages like members, contact form are working fine. Please advise me what to do, the support won’t help me because this is customized theme.