Recovering randomly deleted objects in Active Directory

I was asked this question:

There is a big domain with many DCs in it.
Day 1 : System state backup is taken.

Day 2: Some objects like users are created in the domain.
Day 2: Many of the objects in the domain are deleted (OUs, computers, Users) randomly. So there is no listing of what all objects were deleted. This deletion comprises of the objects that were existing before the backup was taken and also some from the newly created objects.

Day3: The admin gets to know that a large number of objects has been deleted, but he doesnot know exactly how many and which ones.

What should be done to recover the deleted objects?