Hi, I'm Pete. Welcome to JustAnswer! I'm reviewing your question now, and will post back with your reply ASAP.
Please confirm the full make and model number - is it the Sony HDR-CX190?
Yes, I am checking for you now...
This button is out of stock with all suppliers, so the only way to obtain a replacement button is to take it from another camera, e.g. if you were to obtain another camera from eBay: