Your instructions on how to reset my phone to new. Doesn't work!

You have asked us to guess everything about your specific situation.

Examples:

• Do you actually have an iPhone 6S or earlier?
  • If yes, what actually happens when you press the illustrated buttons?
  • If no, you have shown the incorrect illustration.
• What steps have you taken?
• What have you seen?
• What error messages appeared?

“Doesn’t work” doesn’t give us much to go on. What happens when you follow those instructions? And do you have an iPhone 6S or earlier?