I've also done what has happened to you, FlyMS1! If you deleted it from the phone, there is no way to retrieve that number. If you answered a call, you can go to the call records on My Verizon if you recall the date/time you will see it there. So you should be in luck. I'm guessing the person didn't leave a message where you can get the number from the voicemail header?
Follow us on Twitter @VZWSupport