Unmuting comcast DVR

Yesterday, my comcast dvr suddenly went mute. I can see the picture but there is no sound.

Instead of calling comcast which will first make me go through dumb 101 troubleshooting procedures, i googled: comcast dvr unmuting

And I found this fix in 1 min:

1. Press the "Cable" button at the top of the remote to put it into Cable Box control mode.
2. Press and hold the "Setup" button until the "Cable" button blinks twice.
3. Enter code 994. The "Cable" button will blink twice.
4. Press (do not hold) the "Setup" button.
5. Enter code 00141.
6. Press whatever button you want to map the mute function to.

from: here