Thank you Paul.
I tried this about 30 mins ago. Initially a slightly different version of the UI page appeared. The volume control had a number attached to it (not before), the time left indicator was working. So I thought I would try the bass & treble control from the music note button. Amazingly the two slide bass & treble screen had been replaced by a graphic equaliser page. Presumably, this is the download you were advising me to do for one of my other queries regarding audio connection and absence of amplifier control. Following the instructions from the other post I ticked the enable button and it immediately killed the music. I ticked it again to switch off but the music would not come back. I pressed the "Flat" button first to give some content and then enable. Still no music. Also, when I returned to the home page the HDD was paused, the time left indicator had returned to zero and the play button was frozen.
So I ignored the UI and switched off at the mains and the usual commands to select an album to play. There was still no sound. All that was scrolling through on a blank screen was the I.P. address. I tried on/off several times more only achieving a blank display. On about the fourth reboot, sound was restored.
I am reluctant to try enabling the equaliser again until you have responded to this post. I might not get back my music.