This post at the MS forum may help. Worse case scenario would be to download the media creation tool at MS here and create a bootable Windows 10 installation flash drive. To boot from the USB you would press F12 immediately at boot and select the USB drive from the list. You will need to use another computer to create the flash drive.

Manually select the boot device
The first thing to check is which device is selected as the primary boot. To do a quick check please use F11 to launch the manual boot selection.

Restart the system
Press F11 during POST to enter the Boot Manager
Select the correct Hard Disk drive (Virtual Drive), where the OS is installed
Boot from this device
If the system now boots into the operating system, the hardware is fine and there is a boot order conflict in the BIOS settings. The most likely cause for this is that the system is set to boot from CD/DVD and/or USB before the drives, which is a logical setting. To resolve this, just ensure you do not have a USB or CD/DVD inserted into the system.

Note: The Error can be caused by wrong settings in the boot mode, too. An OS installed in UEFI mode cannot boot in BIOS mode and vice versa.
You can change the boot order setting permanently in the System Setup to boot from the drive first. To change this:

Restart the system
Press F2 during system start to enter the System Settings
Change the Boot Sequence in the Boot Settings
Leave the menu via Exit in the upper right corner of the screen
Note: After this, you will require pressing F11 if you wish to boot from a CD/DVD or USB at a later date.