Website and WordPress not loading

As you say you are on a paid support plan, it would be best to open a Technical support case at https://support.console.aws.amazon.com/support/home#/case/create

re:Post is community supported and contributors here can do their best to help you as well.

Your website has been unavailable for two weeks, the first thing to establish is whether it is running on EC2 or Lightsail (or something else).

If it's on EC2 then in the instance in a running state, and if you look in the Monitoring tab is there any sign of excessive resource consumption?

Many years ago I ran a Wordpress website on a free tier EC2 and found that a memory leak in Apache was making my EC2 become unavailable after about a month. The fix was to restart Apache once a week.

Unfortunately the EC2 section of the AWS Console doesn't display metrics for memory use, you'll need to setup CloudWatch agent to collect these https://docs.aws.amazon.com/AmazonCloudWatch/latest/monitoring/Install-CloudWatch-Agent.html

Also, how can I retrieve my backup?

What method are you using for backup?