If it’s an Apple Account you don’t use, didn’t enable two-factor authentication, and — given the usual pattern for these takeovers — potentially reused a password, it’s effectively no longer your Apple Account, and you likely won’t be able to recover it.
You’re left to ignore it, as it is no longer yours.
Unfortunately, if the Apple Account is associated with Activation Lock somewhere, you’ll want to provide proof of ownership to Apple and get those devices relocated to an Apple Account you do use and do have secured.
If there is payment information associated with that Apple Account, revoke that, too.
Enable two-factor authentication on the Apple Accounts you do use, use unique passwords (password reuse is doom), and review any issues reported in the Apple security recommendations.