I don't have access to the phone number registered on my wife's iCloud account

Blangger Said:

"I don't have access to the phone number registered on my wife's iCloud account: I had a number hooked up to my wife’s iCloud and we no longer have that number any way you could help get that account back"

-------

To Get the Phone Number Changed,,,

Contact Apple Support:

Ask the Apple Rep to modify it over the phone. If permitted to do so, then inform to modify the Phone Number associated to your Apple Account, to what it should be. Important: Perform a Trial & Error login session with the Apple Rep prior to ending the phone call.

Contact ApleSupport. 

• Contact Us - Choose Locations
• Proceed from there as Necessary
• Why the Wait: Phone calls are taking a bit to go through at the moment, due to lots of calls. With the Coronavirus Pandemic, many are at home at the moment, with much time on their hands to contact Apple. So, just stay on the line, and you will get through :)

The trusted number was removed from the account , you can add another trusted number from the device , get it verified ( the last step would be click on done to save the settings ) .

See the details in the article Use two-factor authentication for your Apple ID on iPhone - Apple Support

Add or remove a trusted phone number

Adding trusted phone numbers can be useful if you want to use two-factor authentication but don’t have access to the phone number you added when you turned it on.

1. Go to Settings  > [your name] > Sign-In & Security, then tap Two-Factor Authentication.
2. Tap Edit (above the list of trusted phone numbers), then enter your device passcode when prompted.
3. Do one of the following:

• • Add a number: Tap Add a Trusted Phone Number, then enter the phone number.

1. When you’re finished making changes, tap Done.

Trusted phone numbers don’t automatically receive verification codes. If you can’t access any trusted devices when setting up a new device for two-factor authentication, tap “Didn’t get a verification code?” on the new device, then choose one of your trusted phone numbers to receive the verification code.