This is my quick way that I undelete items.
Create a Query on System
On the General tab in the Query select "Include Soft Deleted Records"
Add your attributes (include Soft deletion attribute)
Test, if your missing group shows up as Soft deleted = true
Save the query and add it to the console in a test area.
Run the query, right click the soft deleted record and select Restore
It should be back, good luck!