From the My Phone Service page, scroll to My voicemail and select Set up voicemail. Choose your voicemail box type. Select Advanced voicemail (suggested method), and then select Next. Subaccounts voicemail access and phone number assignment. Add name and assign each phone number a name to easily identify who is using the line. Select Continue.
I know you probably thought of this, but did you ever record the message someplace else or possibly have it playing while shooting a home video during a birthday or an anniversary? Probably a remote possibility, but you never know. Since you didn’t record over it, there might be a possibility of retrieving it. I really hope so! Please let us know what happens.

The following steps describe creating a custom greeting for your iPhone. Inside the voicemail application, tap the Greeting button. Tap Custom. Tap Record and start dictating a voicemail greeting. When you have finished recording, tap Stop. Review the greeting …
Assuming you only care to hear from a handful of people, open your phone’s Settings, and tap on Notifications. From here, tap on Do Not Disturb and toggle it on. Now, you can tap Allow Exceptions and add the contacts you’d like to get calls from.