Completely messed it up

Title says it all really, trying to soft re-set just confused me more. Is there an idiot proof video/step-by-step guide? Better yet, can somebody talk me through it, start -finish, I'm rubbish with technology.

The Vodaphone store I bought the phoned from is an hours' journey each way by bus and takes up best part of the day.

Mastercard purchase 5 Oct. 2025. HMD Arc64GB