The issue you describe is different than the OP issue… you should have started a new topic… on the Activision Support website.
Only watched the 1st minute… the video describes an issue that started yesterday:
- Game crashing losing levels
- Who reset my game to default
- https://us.forums.blizzard.com/en/blizzard/t/loadouts-are-all-gone-just-now-mw2-mw3/49551
The last post on the topic on the US forums says the issue is now solved… try again ? If it is not solved for you, contact Activision Support… we can’t do anything about it here.