Internal hard drive disappeared?

School was out… Shut down my laptop and shut up at the same time. Then I packed it in my bag and left. At home I noticed that he was still running and had overheated in the bag… I shut down the laptop via the I / 0 button.

(Windows 10)

After booting up, my entire HDD (Windows is running on my SSD) just disappeared… Neither in Explorer nor in Disk Management to find… I'm just desperate… Goods 600GB on it o.O

Sounds like your HDD did not survive the heat.
You could upgrade it and connect it to another computer. Although I do not think that you can do much there, but wishers happen.

HP OMEN… Ka if that even works

I think that the hard drive was still working after you apparently shut it down and the shocks caused the HDD to suffer critical damage during transport. Wish I do not do that but try it as others say the HDD times expand and try to another device good luck.

On the bottom of the HP Omens you would need to find 4-6 screws. Try to remove the times and open the notebook carefully.
Take a look at this tutorial:

HP support could help… Over a few diagnostic tests… Seems to be fixed somehow

That's good to hear. Have got off again with a black eye.