Sounds like OP is talking about the carrier-provided blakckberry.net email address.
For what it's worth, K, you can setup, edit the settings for, and delete the carrier-provided email address at the carrier's BIS web portal. See: Where can I log into my BIS account? - BlackBerryFAQ
Or, do it from the blackberry . . . How to add / delete email addresses - BlackBerryFAQ
And by the way, your situation is one reason to be very selective about when to use the carrier-provided blackberry.net address. You can add up to 10 addresses to BIS. Use your ISP address, google, yahoo, windows live, hotmail . . . . whatever.
I don't have a clue whether your alltel blackberry.net address is lost to you now forever or not, but regardless you cannot read email at a carrier-provided blackberry.net address except witht he blackberry.