Forgotten iCloud ID and password

This article tells you the various ways you can try to discover your forgotten Apple ID --> If you forgot your Apple ID email address or phone number - Apple Support Typically an Apple ID is an email address you have used. If you are currently using a mobile device that is logged into your account, go to Settings and tap your name at the top. Look in Keychain, and in a browser's security settings if you use it to automatically sign into Apple when using a browser.

This article outlines what to do If you forgot your Apple ID password --> If you forgot your Apple ID password - Apple Support

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

If you find you can’t sign in, reset your password, or receive verification codes, you can request account recovery (read this support article: 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.

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." Click here --> Contact Apple for help with Apple ID account security - Apple Support

Since the device won't turn on, the conventional means for finding out the iCloud account to which it is signed in is not available to you. Apple does not provide any lookup service except where you are logged into an account and can see the devices that are signed into that account. It does not have one for looking up a device and then the accounts used with that device.

See -> If you can't connect or sign in to iCloud

If you can't connect or sign in to iCloud - Apple Support

B T W:

You are sign in here .  .  .  with your Apple ID & Password.

Your Apple ID is the personal account you use with all Apple products and services. It includes the email address and password you use to sign in, as well as the contact, payment, and security details that you use with Apple.

You can’t merge multiple Apple ID accounts.

What happens when you use the same Apple ID & Password that you use to sign in here?

See the following Apple articles

Sign in with your Apple ID -> Sign in with your Apple ID - Apple Support

Manage and use your Apple ID -> Manage and use your Apple ID – Apple Support (UK)

so I go to service delivery points where it required a iclould I'd password which I had forgotten .

What is a service delivery points?

Have you purchased a 2nd hand iPhone?

I have all the imei number and necessary document of the iPhone,

Then contact Apple support for help, -> Get Support (apple.com)

You have to show proof of ownership of your product, provide all documentation showing your purchase of the device.

If you do not have additional proof of ownership, contact the reseller. They may be able to provide the original purchase document.

Once Apple receive your proof of ownership, Apple will further review your request and provide an update.

See also -> Keep your receipt after you buy an Apple device

Keep your receipt after you buy an Apple device – Apple Support (UK)

Use a web browser and reset Apple ID password If you forgot your Apple ID password - Apple Support

Reset your Apple ID password on the web

If you don't have a trusted device, you can reset your password on the web — but the process might take a little longer.

When possible, the web process redirects you to a trusted device. If you'll have access to one of your trusted devices soon, it might be faster and easier to reset your password then.

Reset your password at iforgot.apple.com

Note : your iCloud credentials will be required to reset password , without knowing correct Apple ID the password can never be reset , if you contact apple support , they don't keep record of Apple ID address as it can be changed by the user any time .