Issue with Lightsail Instance Disappearing

Hello.

Lightsail instances do not disappear automatically.
As AWS re:Post Agent answered, someone may have accidentally deleted your Lightsail instance.
It's possible that you're signed in to the wrong AWS account, but if you're signed in to the correct AWS account, it's likely that you've deleted it.
If you regularly create backups of your Lightsail instances, you may be able to restore from a snapshot.
However, if you have not taken a snapshot, you will not be able to restore.
https://docs.aws.amazon.com/lightsail/latest/userguide/understanding-snapshots-in-amazon-lightsail.html

By the way, it is also possible to search for deleted events from the CloudTrail event history as shown below.
Try searching in CloudTrail for the region where your Lightsail instance was launched.
https://docs.aws.amazon.com/awscloudtrail/latest/userguide/tutorial-event-history.html

There are several possible reasons why your Lightsail instance might no longer be accessible or visible in your dashboard:

1. Scheduled maintenance: AWS occasionally performs maintenance on Lightsail instances, which can temporarily affect availability. In some cases, maintenance issues might cause instances to become inaccessible or not start properly afterward.

2. Resource or configuration issues: There might be underlying resource constraints or configuration problems that caused your instance to fail or become inaccessible.

3. Accidental deletion: It's possible the instance was accidentally deleted, either by you or someone else with access to your AWS account.

To resolve or recover the situation:

1. Check the AWS Health Dashboard for any ongoing issues or maintenance reports that might explain the downtime.

2. Look through your account for any snapshots of the instance that might have been created automatically or manually. If you find a snapshot, you can create a new instance from it.

3. If you had a static IP attached to your instance, check if it's still available in your account, as this might help you locate information about the missing instance.

4. Review your AWS CloudTrail logs (if enabled) to see if there were any API calls related to deleting or modifying your instance.

5. If you're unable to find your instance or recover it through snapshots, contact AWS Support. Provide them with details about your instance (name, ID, region, etc.) and when you last accessed it. They have additional tools and access to help investigate what happened and potentially recover your data.

For future instances, it's recommended to regularly create snapshots as backups to provide a fallback option if issues arise with your instances.
Sources
Lightsail instance does not start | AWS re:Post
Lightsail instance stopped to be reacheable from internet | AWS re:Post
Lightsail Instance - cannot connect after Amazon linux 2023 upgrade | AWS re:Post