Media keys not controlling anything anymore after hardware reset on old Mac Pro

Background service may be disabled:

launchctl load -w /System/Library/LaunchAgents/com.apple.rcd.plist

Found it here.

Hey tangre79,

We'd be happy to help out. If your media keys aren't working anymore, perhaps your function keys are set to be used as function keys instead of media controls. To check, go to System Preferences > Keyboard and check to see if your function keys are set to be standard function keys or not. If they're not, perhaps test things out in safe mode.

For help with doing so, check out: How to use safe mode on your Mac - Apple Support

These steps will get you into safe mode:

Intel processor

1. Turn on or restart your Mac, then immediately press and hold the Shift key as your Mac starts up.

2. Release the key when you see the login window, then log in to your Mac. 

3. You might be asked to log in again. On either the first or second login window, you should see ”Safe Boot” in the upper-right corner of the window.

If you continue to have issues in safe mode as well, it might be best to reach out to Apple Support here: Get Support

We hope this helps out.

Take care!

not sure what keyboard you have but I had the same issues and I am using a logitech keyboard with Logi bolt installed. I closed the application in the CPU section of activity monitoring and every started working again. I opened the app again and everything is working so maybe it just needed a reset.