Hello, I’m Nathan, and I’ll be assisting you today. My livelihood depends on your positive feedback, so your satisfaction is my highest priority.
Sorry to hear you’re having trouble.
There is no need to buy a new phone. You can't reset the passcode to a new one,
but you can "restore" the phone, basically deleting everything from it and starting over as if it were a new phone.
The intent is that after you do the factory reset, everything is wiped out, and then restored from either an itunes (computer) backup, or backed up from the icloud servers.
As long as his data is backed up to either of these, there will be no problem.
Plug the phone into the computer via usb cable, open itunes, click on the phone, then Restore Device, and follow the prompts.