my right siri button doesn't work, how can I restore my iphone12?

Hello Kindkatty1980!

Please make sure you’re following these instructions: If the Restore screen appears on your iPhone, iPad, or iPod touch - Apple Support.

Especially note the instructions in the “Get more help” section.

Have a nice day, and good luck!

If you mean the side button is physically not working, you'll have to get it repaired.