Paul, you need the Yamaha program YEMinstalled on a computer. It's not difficult, and you can load all packs including the original factory installed packs. Download them here

You never actually lose the original factory installed packs, they are still on your keyboard, but you have to activate them again on the keyboard, so no worries about that.
So if you only want to do that:
menu(2)
Expansion
Restore Pre-Installed Expansion Packs

But if you want to include other packs you'll need the YEM program, download all the packs you want installed on the keyboard, and use the full install method from YEM to a USB

Here is a video that should help


I sent you a PM if you need more help. I'm not an expert, but through trial and error, now find the process easy.

Good luck Paul