The humidifier has been working well for the last four days and all of a sudden the display panel is not showing any readings.

Michael A, January 2016

It will be a dehumidifier I'm sure - and you don't say the make or model - but no matter.

If the display does not illuminate then it will be a defective display module or a problem with the power that feeds it to make it work.

Determine the Brand and see if the manufacturer offers a customer service help line - call them.

Good Luck..., January 2016