Sounds like you had maps (probably the G2 maps) loaded to the internal memory and when you did the factory reset it wiped those out. You might need to get in contact with the very helpful folks at
Garmin to find out what maps should have been preloaded, if any, and how to restore them. The alternative is to buy the new G3 maps that were released a few months ago. Frankly, the G3s are better and worth the investment.
John