Resolve 403 Error on WordPress

My WordPress site has suddenly started throwing a 403 error and is now inaccessible. I’m unsure whether it’s tied to a recent plugin, theme change, permission issue, or something at the server level, so I need a specialist who can quickly diagnose the root cause and get the site back online.

Here’s what matters to me:
• Rapid identification of what’s triggering the 403—whether it’s .htaccess rules, file-permission anomalies, a misbehaving plugin/theme, or a server configuration conflict.
• A clean, lasting fix that restores normal access without breaking existing functionality.
• A short summary of what you did (steps taken and the exact cause) so I can avoid the problem in the future.

You’ll have full cPanel/FTP and WordPress admin access (once the block is lifted), and you’re welcome to use SSH, WP-CLI, or any troubleshooting tools you prefer. The job is finished when the front-end and wp-admin both load without errors and all previously working pages function normally.