Someone changed my Apple ID from my device

That usually means the culprit has physical access to your device, your passcode, and your Apple ID.

Or that you acquired this device used, never reset it, and the seller somehow masked the Activation Lock.

Not all that much, really.

You’ve had what amounts to a catastrophic security breach.

If you think your Apple ID has been compromised - Apple Support

If you still have the original purchase receipt showing the serial number, you might be able to re-acquire access to the device with the assistance of Apple.

As for recovering access to the 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

This is also seemingly more of a civil or criminal case. If it’s an option for you, check with a lawyer or with local police.