unarchive process

https://docs.appian.com/suite/help/23.4/Managing_Process_Archives.html#unarchiving

Adding to stefan AFAIK system admin has the access and user with designer access might be able to view not sure he can unarchive . 

There's a plug-in that allows unarchival via an instance ID.  I built myself a tool process model with a start form where I can plug in the instance ID, and now that we can see archived instances in the process monitor, it gets pretty easy to find the ID too (it used to be a nightmare).

You can use plugin  https://community.appian.com/b/appmarket/posts/self-service-process-unarchive-sspu .

 If you have access for appian support, raise a ticket. They can unarchive.