I have mentioned this in the comments of my question. As this one is anyhow duplicate.
So the oldest known copies of Atharvaveda and Rigveda (2 of the 4 books) are kept at the Bhandarkar Oriental Institute in Pune, Maharashtra. These two manuscripts are written in Sanskrit and were found in Rajasthan during the late 1800's. They are dated from around 12-1300 AD and thus preceding any major Persian influences.
These manuscripts are included in the UNESCO list of world heritage sites and are commonly expected to be priceless treasures for all of humanity.
Thought I am unsure of the other 2 books (Samaveda and Yajurveda).
And as a personal opinion most of the scripts I guess are lost during the time due to war between religions and other natural or man made causes.