suddenly lost all sonogram & mp3 files

[ThickKnee]

Hi All.
Our installation has suddenly stopped generating the files that store the bird calls and sonograms.

The detections are being performed and the stats are recorded but no sonograms can be displayed and the extracted by date folder is completely empty.

All historical mp3 and sonogram files have been deleted. All we can do is view the stats. We cannot listen to any detection.

We are in the habit of restarting all services at the start of any recording/detection session. The free space on the SD card is 1.1Gb.

Can anyone suggest what the problem is? Ta.