The community is also a great place to check out. Try these places for help from other users:
If you're encountering issues when launching or playing Call of Duty: Modern Warfare 2, make sure everything installed correctly.
Exit Steam entirely.
Browse to your Call of Duty: Modern Warfare 2 installation folder (Usually C:\Program Files\Steam\steamapps\common\call of duty modern warfare 2\)
Run the following installers:
Reboot your computer and test the issue again. If the issue persists, contact Call of Duty: Modern Warfare 2 support.
To view the additional DLC content for this game that is registered to your account, please do the following:
Once the DLC is purchased, it will be automatically installed to your game and be available to you in multiplayer. Currently, the Resurgence Pack maps are only available in the two special playlists listed at the bottom of the selection screen.
VAC bans are not negotiable, and are issued and enforced regardless of the circumstances under which the cheating infractions were recorded. Steam Support cannot remove a VAC ban in any case.
You can find more information about the Valve Anti Cheat (VAC) system here:
If you encounter a cheater in a game, you can report them using their Steam Community profile:
Do not use the Steam Support ticket system to report a cheater. The method that is outlined in the Reporting Suspected Cheaters link is the best way to report a potential cheater.
In addition to the required ports for Steam, Modern Warfare 2 requires the following ports for multiplayer:
For more information please see this page.
If the above does not resolve the issue and you are running Windows 7 or Windows Vista, please complete the instructions in our Windows 7 and Vista Troubleshooting FAQ.
If you are running in Windows XP, take the following steps: