Happened to me. Researched, & said if you dont close your game properly, the server might not save everything. It could either erase progress from the last time you opened the game or wipe it completely. It depends I guess. Its whatever, dead game is dead.
Here's the games security policies: Activision Support
To go from level 10 to level 1?
Maybe you were caught...
Any user who colludes with another user to exploit the game for the purpose of gaining XP, game score, weapon level, or in-game unlock is subject to penalty.
- First Offense: User will be temporarily banned from playing the game online, will have their stats reset,and will have their leaderboard entries deleted.