Infinity Ward is currently working to address an ongoing issue in Call of Duty: Modern Warfare. The most recent title update caused a major problem leading to players' in-game stats being reset. This involved a fear-invoking prompt telling Modern Warfare players that they have to accept resetting their stats in order to play whatsoever. Infinity Ward has since made some progress on the bug, but it's not fixed in its entirety. Some players won't be getting their stats back, however.
The crux of the issue is that the most recent title update somehow led Modern Warfare to believe players' stats had been corrupted. Modern Warfare wasn't able to correctly read those stats into the game. As such, it prompted players to either click "Yes" and reset their stats or click "No," which prevented them from playing the game. Knowing Modern Warfare players clicked no and decided to wait 24 hours before trying again. But many players also clicked yes, erasing their stats across their combat record, leaderboards, custom classes, and Operators.
Infinity Ward has gotten rid of this yes/no prompt and fixed the stat "corruption" that the game was interpreting. This update was made in Modern Warfare's backend, from Infinity Ward's side of things, so players won't have to download an update to have the fix. Everyone who clicked on "No" and waited can now login and play the game, their stats fully intact.
As for players who clicked "Yes" and reset their stats in order to play yesterday, Infinity Ward doesn't have a solution yet. For the time being, those stats continue to be erased. According to Infinity Ward, a fix is being actively worked on. Infinity Ward does warn that all stats between the patch and when the fix goes live may be rolled back to the player's previous stats, if and when that happens.
One thing that Infinity Ward wants to make clear is that no actual Modern Warfare progression has been erased or reset. Whether it's players' rank, XP, Battle Pass progression, weapon progression, unlocks, purchases, or otherwise, they haven't been altered in the slightest. Only stats were affected by the yes/no prompt. Part of why this bug went viral was due to worries over lost progression, but that's not happening. Stay tuned for more information when Infinity Ward provides its next update.
Call of Duty: Modern Warfare is available now on PC, PS4, and Xbox One.