Thank you for your answer.
Yes, I know midi is not audio. I am not good at this, but I know it. The fact is that, till yestarday, I was able to hear all midi projects, but know, I am not. Being an ignorant, sometimes is hard...
Are your midi tracks properly pointing to [aka routed to] a sound producing device (such as a hardware or software synth)?
I have some midi tracks downloaded from learnchoralmusic. I used it till yesterday with no problem...
Is your mini piano hardware connected to your PC that you use to record midi note data in a DAW such as Cakewalk and then play back on the hardware from the DAW?
In preferences, Midi/devices/ out, I have selected my Audiobox usb (as usual).
Thank you again, in advance...