Hi,
This issue may occur when your hard disk drive has failed, or the boot partition of your hard drive has been wiped out or got corrupted.
Power up your PC, as soon as you see the Toshiba splash screen, press the 'F2' key at the top of the keyboard to enter the BIOS CMOS Setup. If your BIOS is showing that the HDD/SDD is not present, then your hard disk drive has likely completely failed.
Try these steps and should you need further assistance please contact Toshiba Support.
Regards.