hello, i forgot my son's apple ID, but we remember password. now we have problem with phone and i need icloud to resolve it, but cant remember ID, what can we do? ((

See the following Apple articles:

Set up an account recovery contact

Set up an account recovery contact - Apple Support

How to use account recovery when you can’t reset your Apple ID password

How to use account recovery when you can’t reset your Apple ID password - Apple Support

Help a friend or family member as their account recovery contact

Help a friend or family member as their account recovery contact - Apple Support (IN)

👉 you can help your son.

How to generate a recovery key

How to generate a recovery key 

👉 FYI: Write down your recovery key and keep it in a safe place.

See if you can recover the ID. An iCloud e-mail address is an Apple ID. Use every email address you can think of.

Apple ID - How to find your Apple  -  

Apple ID - Find  -     

Other ways to find your Apple ID

You can check to see if you're signed in to the App Store, FaceTime, or Messages on your iPhone, iPad, iPod touch, or Mac, or check to see if you're signed in to iTunes for Windows on a PC. You can also go to iCloud.com or appleid.apple.com and see if your Apple ID prefills on the sign-in screen.   

Hello ~ Take a look here:

If you forget your Apple ID or password

~Katana-San~

I have a passwerd but i forget apple id