NAVIGON U.S. West

I had same problem, had added on central and after updates lost my west maps. Called Garmin customer support (you will find number through app store - just follow app support link). They had to reset something on their end. They will need info on your phone that comes from iTunes

I bought it after all these maps disappearing problems I see in the pervious reviews, and it works fine. The best nav app have seen and tried on iPhone.