Each uasset is a map actor, the folders are the way UEFN stores all these
I have no experience with using autosaves
As per ClockworkOcean’s suggestion
Go to User/Documents/Fortnite Projects
Copy your maps folder somewhere for backup and copy the Autosave content somewhere else to back that up too.
probably locate the umap file in User/Documents/Fortnite Projects/Yourmap/Plugins/Yourmap/Content
you could replace it, but without all the other content it may not work if it is dependant on certain uassets…
All the uassets, are located in the either the ExternalActors or the ExternalObjects folder in this directory,
I would be inclined though to first open the latest snapshot map as usual from the editor
You will be able to copy the uassets in bulk from windows explorer and paste them into your map or its Content Browser
Make another snapshot with URC, then close UEFN and replace the umap file, see if it opens in editor