Dell Inspiron 7520 knobs not working

The three knobs at the upper right corner of the laptop (for Dell instant launch, audio and mobility center) in my Del Inspiron 7520 are not working. When I press any one of them, the knob lights up for a while, then nothing happens. I have checked via Dell Update that all my drivers are up to date. I have also run a diagnostic and everything seems to be OK. Running on win 10. Thanks for any inputs!