Calibre Library - Restore a Library From Previous Folder Instead Of Export Function

Start by positioning your old library

1.  Copy/paste the old library folder to the destination folder. Do not worry about the current name because it will be renamed after the complete move.
2. Create an EMPTY utility folder.

Create a new Empty Library Folder on Calibre

1. Click "Switch/Create Library"
2. On "New Location" browse for the "EMPTY " folder you created previously and click on "Select folder"
3. Now select option 2 "Create an empty library" > "Ok"

Restore a previous Library

1. Click "Switch/Create Library"
2. On "New Location" browse for the old library folder (the one you want to restore) > "Select folder"
3. Now select option 1 > "Ok"

Rename the old library with your new desired name

1. Select any other existing library to free the one you want to rename
2. Go to "Rename library" > select the previous library > type the new name
3. Cleanup and remove the empty folder