Windows 8 Operating system not found

On the new systems, because of perceived user mandates, the startup is so fast it doesn't slow down to see if you need something. I do not have a Viao, but there should be some key combination to allow you to get into the bios. On some systems, you hold down a key which you turn on the power. If you could find such a procedure for your unit, perhaps you could get into the bios.

If all you did was format the drive, it might make it impossible for Windows to install because partitions are already on the drive. Since we cannot tell your exact configuration, maybe you could find some way of describing the exact configuration of the drive, and what options you have as far as recovery and/or external media.

I've restored the hard disk to a single partition and completely erased it.

If you are working in UEFI, the install needs at least two partitions. If you are installing Windows 8, and you drive has already been wiped, it may have to remove any partitions and install. Then you can shrink the OS partition if you want.

But still just guessing due to lack of information about your system configuration.