Typically once you delete them they're gone. See here: http://www.verizonwireless.com/support/voice-mail-faqs/ You can only retrieve the voicemail if you're still on the line. In other words you called your voicemail and you deleted them, but didn't yet hangup. In that instance you can recover the message. If you'd still like to try anyway, you can dial *86 on your phone to dial your voicemail, and listen for an option to restore/recover deleted voicemails. However as I stated previously, you're most likely going to be unable to do it if you've already disconnected that call from which you originally deleted the messages. Hope that makes sense.
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