i need to change my icloud password of lost device

Exactly how you change your password depends upon if this is an adult or a child, and the equipment you have. Click on this link to learn how to change your Apple ID password --> Change your Apple Account password - Apple Support

This is how you change your Apple ID password on your iPhone, iPad, iPod touch, or Apple Watch:

1. Tap Settings > your name > Sign-in & Security.

2. Tap Change Password.

3. Enter your current password or device passcode, then enter a new password and confirm the new password.

Forgot your password? Go to --> If you forgot your Apple Account password - Apple Support

4. Tap Change or Change.

If your other devices do not update to the new password, reset the password again and this time say “yes” when it asks you if you wish to sign out on other devices too. Read this thread I changed my Apple ID password--how do I … - Apple Community

If Apple tries sending you a verification email and you do not receive it, read this support article --> If you didn’t receive your verification or reset email - Apple Support

"When you make certain updates to your Apple ID, we’ll send you an email to help you complete the update. For example, you might have reset your password, reset your security questions, or added a new email address to your account."