Check to verify that the features are still programmed on the buttons. You can do this with Feature *0 and pressing the buttons. Try to manually do a feature button. Feature 86 will provide background music and Feature #86 will turn it off. Feature 85 will put your phone in DND and Feature #85 will restore it.

The other thing you might try is to unplug your phone and plug it in letting it set up several time to reset the port.

Also try swapping the phone with another extension to see if it is the port or the phone. Does the trouble move with the phone or stay in the same place. It is the phone if it moves with it or the port if it remains in the same place.