Can I use my iCloud to help a friend reset his iCloud password if he forgotten it and lost his phone?

Hello,

This Apple article has instructions for what to do if you have forgotten your password --> If you forgot your Apple ID password - Apple Support

or go directly to this link --> http://iforgot.apple.com/

If you still need help:

Contact Apple for help with Apple ID account security "This article provides country-specific Apple Support contact information for customers seeking help with their Apple ID password or other security-related issues." --> Contact Apple for help with Apple ID account security - Apple Support

If your friend's only trusted device is the lost iPhone, the person will need to try account recovery.

If you find you can’t sign in, reset your password, or receive verification codes, you can request account recovery ( How to use account recovery when you can’t reset your Apple ID password - Apple Support ) to regain access to your account. Account recovery might take a few days or longer, depending on the specific account information you can provide to verify your identity.

Hi there, I believe the best place to learn about this is here > Set up an account recovery contact - Apple Support. Feel free to follow up with any questions!