Restoring ec2 root volume from a snapshot is just a two-step process.

Pre-requisite :

• Make sure you have a snapshot of the attached root volume.

Steps-to-do :-

• Click on the instance in aws console > Under Action menu > Monitor and Troubleshoot > Replace root volume
• select the snapshot to restore, and a task will be created
• Task will be completed within a minute, check the task status from storage tabs.