When the thing not owed is an immovable or a corporeal movable, the person who received it is bound to restore the thing itself, if it exists.
If the thing has been destroyed, damaged, or cannot be returned, a person who received the thing in good faith is bound to restore its value if the loss was caused by his fault. A person who received the thing in bad faith is bound to restore its value even if the loss was not caused by his fault.
La. C.C. § 2304