How to gather the extension attributes values for Migrated User accounts from ADAM ADLDS Database

What are you really trying to do and why? 

This is for Knowledge purpose, If I migrated the user accounts with the service attributes of extension attributes example 8 and 9 to target Domain and due to some other application related issues updated the some values in the same extension attribute 8 and 9 in Target side, now how to recover those values from ADAM ADLDS Database.

The information you would pull from the AD LDS would not be readily usable for the purpose of restoring the Service Attribute contents.

It would be quicker and easier for you to save (and restore as necessary) these attributes by backing up Active Directory regularly using something like Recovery Manager for Active Directory.

Thanks John for saving me from writing that. 

There are two service attributes, by default ext14 and ext15. Ext15 is the matching attribute. It contains the source objectGUID as a string. Ext14 is the aux attribute and most of the time the values are the same for all objects. It really only comes into play when the collision rules are in play. 

if you find that attributes have become corrupt; you can clear both of the impacted object(s) and execute a migration session. That will repopulate the attributes.