Cubase 10 - no sound

Hello there,

First of all, I’m just furious at the moment, I’ve been working on a project and started to sound good. I’ve unplugged my speakers and plugged in my headphones. Guess what? The sound is gone. There is a visible signal, if I render the project the file is fine. Even if I add a new audio file or instrument to the project those have sound. Everything else before is completely silent.
I have no idea how to fix it.

you really don’t supply any info about your system so how could anyone tell you what is wrong when there is now way to know even what Cubase version your use? mac, windows, soundcard etc etc etc…

but let’s go for the stupid suggestions:

is your headphones volume turned up?
is your headphones using a different output than your speakers?