When booting up your computer, enter in the "Advanced Options" menu and do a system restore from there to before you got the virus.
If that doesn't work, consider doing a fresh install of your operating system after backing up your hard drive to recover the files.
You can not enter the Advanced Options when booting the computer in Windows 8.1. This has to be set up prior to doing this, like setting the computer to boot into Safe Mode at the startup. And it's obvious that this will not be an option as the screen is black.
Edited by dc3, 11 October 2015 - 10:00 AM.