Isolate the symptom
Check the selected input, volume and mute setting. If possible, try a different source. Knowing whether one source or the whole system is affected helps narrow the conversation.
LET’S GET IT
WORKING AGAIN.
No picture? Missing sound? A remote that no longer does what you expect? A clear account of the problem gives us somewhere useful to begin.
THE DETAILS / TROUBLESHOOTING
Retrace the change
An outage, a new device or an altered setting can provide a clue. For intermittent issues, record the room, source and time rather than relying on “it sometimes stops.”
Preserve the settings
Avoid factory resets unless the manufacturer or installer recommends one. They can erase system configuration. Tell us what you have already tried so we can discuss a sensible next step.