Hi Robbert,
Thanks for posting this question in Microsoft Community.
I can imagine the inconvenience you have experienced. I will definitely try and help you in fixing the issue.
What is the make and model of the computer?
You may try to boot from the Windows 8 DVD and try performing an Automatic repair from Windows Recovery Environment (WinRE).
To perform Automatic repair on Windows 8 computer follow these steps:
a. Insert the media such as (USB or DVD) and restart your computer
b. Press F12 key (typically this is F12, but it can differ between computer manufacturers)and choose the drive that you inserted the installation media into.
Once the Windows Setup window appears, follow these steps:
c. Click Next and select Repair your computer.
d. You will then see a blue screen and an option to choose. Choose the option Troubleshoot and select Advanced options.
e. You may choose Automatic Repair from Advanced boot option.
If you are still facing issues then you may try performing a check disk booting from the DVD by following above steps..
a. From Repair your computer choose the option Troubleshoot and select Advanced options.
b. You may choose Command prompt.
c. At a command prompt, type the following command, and then press ENTER
chkdsk /f /r X:( drive letter)
d. Press Y when you are prompted to check the disk the next time that the system restarts.
e. Restart the computer.
Note: When you run the check disk, there are chances of losing data so you can take a backup before running checkdisk.
Important: While performing chkdsk on the hard drive if any bad sectors are found on the hard drive when chkdsk tries to repair that sector if any data available on that might be lost.
If the issue persists you may also contact the manufacturer.
Hope this helps and provide us with more information if you need further assistance. We will be glad to assist.