Watch the video:

0:00 - Explanation
0:29 - Fix controller not working

The issue

Call of Duty: Modern Warfare 2 is currently in Beta and so has a lot of issues, including issues with Steam and their Controller API, phone numbers, etc. Modern Warfare and Warzone were unavailable on Steam, so it’s somewhat understandable that things aren’t working as they used to. This is no excuse, however. Hopefully, this should be fixed in the future, before the full release.

For now, there is a workaround

The fix

All you need to do is disable Steam interfering with your controller. Usually, Steam allows you to remap buttons and customize everything to make it more user-friendly. MW2 does not like this and prefers just a plain-old regular controller. So that’s what we’ll do.

To stop Steam messing with your controller settings, we need to disable Steam Input.

• Open Steam
• Right-Click Modern Warfare 2
• Click Properties
• On the CONTROLLER tab, select Disable Steam Input` from the dropdown.

You should now be able to re-launch Call of Duty: Modern Warfare 2 and immediately regain use of your controller. Annoying, to say the least - especially if you need to remap buttons or use extra hardware to make it more accessible. Steam has done a great job of allowing customizability and lots of controller support, but for now, we need to go back to trusting the game developer.