By default, the root volume of an EC2 instance will be deleted if the instance is terminated. It can only be terminated automatically if its running as a spot instance. Otherwise it can only be terminated if you do it.
Now with that in mind, EBS volumes are not failure proof. They have a small chance of failing. To recover from this, you should either create regular snapshots of your EBS volume, or back up the contents of your instance to s3 or other storage service.