Do you know what the file-names and folder-locations are?
If so then you can create a new blank file, import the files into it and then save it under the new location.
If you don't know what they are then you'll need to first run an Action to collect all the file paths, and then perform the merge using the method I described above.
Bear in mind Acrobat is designed for very light duty automation. Restart Acrobat every hundred or so files; whatever you do, make it so it can restart easily and often.
Thanks for your reply.
Can you please give coding for the above.
No, not really. This is a complex tool that you can develop yourself or hire someone to do for you.