well, with no drives there, it would go to bios.
Did you try restarting PC after it showed the currsor?
Is this a custom made PC or brand name?
If brand name, what make/model?
If custom, what motherboard?
Its possible the boot method has swapped and all you need to do is swap it back to normal.
Its possible the hdd with the boot partition on it stopped working
Do you have a win 10 installer? could boot from it and see if your drives still show up in cmd
Installer - On another PC, download the
Windows 10 media creation tool and use it to make a win 10 installer on USB
Boot from installer
On screen after language choice, pick repair pc, not install
Pick troubleshoot
Pick advanced
Pick Command Prompt
Type
diskpart and press enter
Type
list disk and press enter
This will show the list of drives currently attached to PC, are they all showing?
screenshot might help. (upload to image sharing website and show link here)