Lost the Apple ID and Passcode

Hello Hi,

I gave one of my iPhones (6 Plus) to my daughter and she changed the Apple ID and Passcode years back and now she cannot remember exactly the Apple ID and the Passcode. As we were trying to unlock it with possible ID's and Passcodes repeatedly the phone got locked.

I purchased this phone in Saudi Arabia as we do not have any support in Sri Lanka can you please advice me on how can I get my phone recovered?

I would greatly appreciate any help.

Thank you and best regards,