Corrupt save game

Almost certainly not - uncorrupting any computer file is like unscrambling an egg! If the incident happened while the save was being written out, it will be half updated and half not.

You could ask the good folks in User Mods to look into it, they probably know more about save file structure than anyone outside the devs.

Sorry for that happening to you!  

I know very little about consoles, but if you can retain or copy that save game files somewhere, then try this:

- uninstall the game from the XBox

- clear the XBox cache and game files (save game data)

Clearing Cache and Deleting Files on a PlayStation, Xbox, or PC

support.activision.com
- install the game again

- test with a new city

- if that works, restore the problem save and see if it loads now

Good luck!