If you discover the WordPress theme editor missing from the Appearance drop-down menu, follow these four steps to re-enable it:
1. Double-check that your selected theme is fully activated
2. Adjust your security plugin settings
3. Access the ‘wp.config.php’ Code Editor and modify the ‘disallow file edit’ code
4. Deactivate all of your plugins and reactivate them one by one
00:00 - Start
00:25 - Step 1: Activate your theme
01:04 - Step 2: Inspect security plugin settings
02:55 - Step 3: Update 'wp.config.php' file
04:28 - Step 4: Deactivate and reactivate all plugins
IMPORTANT NOTE: Some users will notice that their Plugin File Editor is also missing. Following these same four troubleshooting steps will enable both the theme and plugin file editor.
Full blog post: https://nichetwins.com/wordpress-theme-editor-missing/
