How to restore a workflow from backup

[Kota Sreenivasa Shravana Kumar]

I have modified a workflow and I have taken a backup of a workflow before publishing the same.

I need to restore the backup workflow due to some issues. Can someone guide me step by step process to restore the workflow. 

I have been searching for a Atlassian documentation on the same but could not figure out one. 

Thanks 

[Nic Brough -Adaptavist-]

Copy the current workflow scheme to a new name

Edit the new workflow scheme - where it currently says "use workflow X for this issue type", change it to "use backup of workflow for this issue type"

Go to project admin and swap the project(s) over to the new workflow scheme.

[Anand Sanke]

How to handle if existing workflow scheme is associated with 1000s of projects?

Can we update active workflow scheme with backup workflow?