are you using twenty twenty two ?
IF so you have to add menu through the theme editor. It is a block in FSE enabled themes.
If you go to template parts and heading you should find the block.
In my guess, you’re using a custom theme that has menu hardcoded as HTML, for the missing menu option, either menus support is being removed by theme or plugin. or you have issues in core files.
Follow these steps to identify the problem:
1. Make a complete site backup before doing any testing.
2. then switch to twentytwentyone theme and see if you’re able to see Menus in the admin sidebar. if not then go to Dashboard>Updates and reinstall the WP version.
3. if after reinstalling wp version menus come back then switch back to your old theme and check if you’re able to see the menus page or not.
4. if after without reinstalling you were able to see the menus then it’s your theme problem.
5. if after reinstalling you got the menus page back then switch to the old theme and check if you can still see the menus or not, if not then definitely the theme issue.
6. if all of the things doesn’t work then switch back to twentytwentyone theme and start deactivating the plugin one by one and see if the menu comes back on deactivating any plugin.
