Troubleshoot Wordpress Access Issues on AWS

My Wordpress site is currently down and users are experiencing 'Access Denied' messages when attempting to log in. The situation is urgent as the website isn't loading properly for me either; it just appears as a blank page. There have been no recent updates to plugins, themes or server settings that could have caused this issue.

I'm looking for an expert with:
- Deep knowledge of Wordpress and AWS
- Experience troubleshooting server-related issues
- Capabilities to restore website functionality quickly

Please provide a detailed proposal on how you plan to resolve this issue.