My amazon aws ec2 instance disappeared or got replaced

Hello.

Is it possible to find the event in which that EC2 instance was created from CloudTrail's event history?
You should be able to find a "RunInstances" event in CloudTrail's event history if it was created within the last 90 days.
I think the event also includes information such as which IAM user created it.
https://docs.aws.amazon.com/awscloudtrail/latest/userguide/view-cloudtrail-events-console.html

You can also search for EC2 deletion events using the "TerminateInstances" event.

If these operations are being performed by a user you do not know, there is a possibility that unauthorized access is being performed, so please delete the IAM user in question.
https://docs.aws.amazon.com/IAM/latest/UserGuide/id_users_manage.html#id_users_deleting

Or please deactivate the IAM user.
https://docs.aws.amazon.com/IAM/latest/UserGuide/id_users_manage.html#id_users_deactivating

You may be looking at a different region, so try searching for EC2 in global view from the URL below.
https://us-east-1.console.aws.amazon.com/ec2globalview/home?region=us-east-1#

If EC2 has been deleted, if a backup of EC2 such as a snapshot remains, it is possible to restore data up to the time period when the snapshot was created.
However, please note that you will not be able to restore if there are no snapshots left.
https://docs.aws.amazon.com/prescriptive-guidance/latest/backup-recovery/restore.html