Contacting the nurse aide registry of whatever state you are certified in would be a good place to start.
Something to keep in mind is that each state's nurse aide registry is different and only deals with its own business. So where one state may have a certification card, another state might have some other kind of documentation verifying your status on their registry. I work for West Virginia and can tell you that their registry offers a document through their website instead of a card.
How you receive the certification can vary too. Again, West Virginia nurse aides find their certification online and are encouraged to print it to have a physical copy. Other states may do something similar or send things by mail. Or some states may charge for it. I wouldn't know which state does what and how though, so one may have to do a little digging for that information.
Also, each state can only certify you or give you proof of your certification in their own state. Meaning, West Virginia's registry only applies to the state of West Virginia. Nothing automatically carries over to Virginia (or the other neighboring states) nor can the WV registry change or process any nurse aide records within the neighboring states.