How to add a menu in Wordpress?

Question

WordPress

The menu is not added to the site on Wordpress. Although it has been created. No matter how hard he tried.
Self-written template. Initially, the menu was, everything was fine. Then there was a need to add a multilanguage, I decided to turn to the Polylang plugin. There added two language versions of the menu. After that, the menu ceased to be displayed in principle in any language. I removed the plugin, nothing has changed. And how to add now is a big mystery to me.