How do I recover multiple iCloud accounts
How do I recover multiple iCloud accounts and all data
iPhone 13, iOS 17
What you are referring to as an iCloud account is an Apple ID.
For recovering access to your own Apple ID:
If you forgot your Apple ID password - Apple Support
If you forgot your Apple ID - Apple Support
How to use account recovery when you can’t reset your Apple ID password - Apple Support
Contact Apple for help with Apple ID account security - Apple Support
For data recovery, that depends on what backups were done, and to where.