|Quoting QR332 (Reply 2):|
If you want to restore parts of your region open the city, and there should be in the first tab of the three a button which demolishes your entire city... click it and it will be restored.
As for cities, sorry, not really sure.
Doing so will destroy the city, and leave you with the original terrain beneath it, there is no way to revert to a previous saved state.
To install a downloaded city, copy it to your "downloads" folder inside the simcity folder in my documents, then in the game select the square you wish to place it in on the map, and select insert downloaded city. You can then select the city to insert.
I dont have SC4 at hand right now so those instructions might be wrong, ill check when i get home if your still stuck ...