Jordan01,
MW2 tracks your stats to utilise it in their matchmaking system.
This means if your accuracy, K/D or amount of headshots is really high,
you will no longer be able to join regular matches.
You have 2 options to fix this solution.
1. Is to delete your stats (you will lose everything)
2. is to modify your stats back to a normal level.
You can google solution 1, but we don't support solution 2 since VAC could act up if you use software to modify your stats.
Good luck