Hi @shoaib9800 ,
Here is a link to the [http://h10032.www1.hp.com/ctg/Manual/c03659338|service manual] for your laptop.
The touchpad is part of the top cover assembly.
Here is a link to a [https://www.ebay.com/p/HP-EliteBook-8470p-Palmrest-With-Touchpad-Fingerprint-686964-001/2255038243|supplier] of the top cover. It is not a recommendation to use them. It is shown to give an idea of the cost of the part. There may be others that may suit you better.
Look online using the part number 686964-001 to find suppliers.
Hopefully this is of some help.