upgraded to iPhone 6, now it says it's a "new" phone, wants password

I have an iPhone 6. I upgraded to latest version (IOS 9.0.2) and now it will only open as a "new" phone...page says "Hello" then asks for password, which I don't have. I have restored and backed up several times, does no good. Sometimes it says there's a problem and it can't back up. I have no idea what else to do.