Restore Hidden WordPress Menu

My WordPress site’s top navigation has vanished— the entire menu simply isn’t displaying. This started right after I added new content that included a small block of custom code, so I suspect either that snippet or a related CSS/JavaScript conflict is hiding the menu.

I need someone to:
• Locate the exact cause of the missing menu (theme file, plugin conflict, custom code, or stylesheet rule).
• Restore the menu so it appears correctly on all pages, both desktop and mobile.
• Keep my existing design, links, and styling intact—no visual regressions elsewhere.
• Provide a brief outline of what you fixed so I can avoid the issue in future updates.

You’ll have full WordPress admin and, if needed, FTP access. The site runs the latest WordPress core and standard plugins; nothing exotic beyond the recent custom code addition.

If you’ve debugged display issues like this before and can deliver a clean, working solution quickly, I’m ready to get started right away.