It looks like the MBR or GPT that tells the BIOS/UEFI where to start booting has been messed up. If you created restore media before upgrading to Windows 10, I'd use that and start all over. If not, you can go here to download or order your recovery media.
You need to download and prepare a Windows 10 TH2 Bootable USB (for UEFI BIOS) using another computer:
Ensure UEFI and SecureBoot are enabled in the BIOS setup.