Q: My Dad forgot icloud password

If you forgot your Apple ID password - Apple Support

If you forgot the answers to your Apple ID security questions - Apple Support

The next best thing if you haven't done so is contact Apple support and see what they can do for you over the phone.

If you get everything sorted out you may want to enable two step verification to make it easier for next time.

Call Russian Apple. The answers are in the same language and your dad didn't answer those in English, otherwise it is him who d ask that question here.

"International" Apple does not exist and they are all available under different phone numbers for the respective countries.

Contact Apple for support and service - Apple Support

Contact Apple for help with Apple ID account security - Apple Support

While they can't setup repairs out of their countries they help with apple id problems internationally, you just need to reach them. English speaking apple support for example would not have access to russian keyboards to try your answers (if they were in russian). Your answers were most likely in the language you are comfortable with and I would guess 99% odds were russian as well as questions, but you are more then welcome to try for international calls - you are the one paying after all, nobody else.