Output media bay - Cubase Master Output is not working

All the tracks are playing the MIDI, but nothing is coming out from CUBASE …! Can anybody help?
If I import an MP3 or audio file , , that one I can hear it , but MIDI is not functioning

How is media bay (in the thread title) connected. Aren’t you playing in the project window?
What track type is this…midi or instrument? Have you loaded an instrument?
Where did the midi come from?

Hi Grim , Thank you for your answer.
I import a MIDI file into as a new project.
I play in the project window yes !
All the trucks are singing, ( I can see signal each truck visually ) on the master as well but I can not hear anything on my speakers or headphones
All set up on Outputs from Studio ( audio connection / Studio Set up ) are OK.
Is strange that if I play a audio file outside the Cubase , the sound board is functional . means connection with windows of the audio sound bord is connected and functional

Why is it strange as you also said?

If I import an MP3 or audio file , , that one I can hear it

Is audio working or not? I thought it was only midi that doesn’t play?

What is the Output of the MIDI track?

I think this is a case of trying to play a MIDI file without an actual instrument assigned to play it.
A screenshot of the Inspector might help.

Thank you guys. I think I solved this problem because the Master channel on Mix Console was not routing correctly. Now I have sound out.

The instruments has been assigned. Even I have no idea where the Library is ! I think I have move it accidentally.