Re: Keyboard making no sound. I have a Tyros 4 and have been caught out many times by ...
... having a Footswitch to control the VOLUME of the keyboard. I have Yamaha AR80 Organ, and on an organ this is called the EXPRESSION PEDAL. When I play something i sometimes 'fade it out' at the end using the Volume (Expression) Pedal.
Then when I come back later and find my Tyros 4 has no sound it takes me a good 5 mins to realise that my Volume Pedal is still on ZERO VOLUME.
Hugh