How to recover an Apple ID that is "Not Valid"?

Which "this? The iPhone? The ID?

Her Apple ID does still exist unless she very intentionally went through all the steps to have Apple delete it. She simply needs to log in on her replacement iPhone, any other computer hardware she owns, or into iCloud.com to see her content. Read this support article to learn how to sign in with your Apple ID on various kinds of devices --> Sign in with your Apple ID - Apple Support

For an Apple Mobile device:

1. Open the Settings app.

2. Tap Sign in to your [device].

3. Enter your Apple ID and password.

4. If prompted, enter the six-digit verification code sent to your trusted device or phone number and complete sign in.

Read this support article about what to do if a iPhone or iPad is lost or stolen -->

If your iPhone or iPad is lost or stolen - Apple Support

- The Find My service described in the article is the only recovery feature Apple offers. It must be set up before the device is lost.

- Note that if you remotely erase your device as instructed in this article, if you subsequently remove it from your account as in this article --> Check your Apple ID device list to find where you're signed in - Apple Support , then according to this article --> How to remove Activation Lock - Apple Support you remove activation lock from the device. Do not remove it from your account. If you do then a finder or thief will have an unlocked device that can be used by another person.

For help with that you need to contact Apple.

To reach Apple Support for an account issue:

1. Click here --> https://getsupport.apple.com/?caller=cups&PGF=PGF63005

2. Select: Disabled Apple ID

3. Select: ”The Apple ID is not active" alert

4. Select: “Continue”

5. Select a chat or telephone call option.

or:

Contact Apple for support and service by telephone --> Contact Apple for support and service - Apple Support