Actually this new update have some problem with graphics drivers. It doesn't work with old Intel graphics drivers. So if you are also facing same blank screen problem after upgrading to windows 8.1 then follow these steps to make your system work perfectly.
Steps:-1. Restart your PC and enter in safe mode (On my laptop I entered in safe-mode by repeatedly pressing F8 key)
2. How to enter in safe mode:-
i) Press F8 or a specific key according to your system
ii) Click on "advance repair option" & then Click "Troubleshoot"
iii) Now in Advance Option under troubleshoot & click Restart (select window startup settings)
3. Safe Mode will work perfectly. Now if you want that your system also work in normal mode then disable intel graphics driver from device manager and restart now everything is OK.
4. You can go to device manager by selecting properties after right click on "My Computer" icon
5. Now it's time to download updated drivers for windows 8.1
6. Intel Graphics - http://downloadmirror.intel.com/23323/a08/Win64_15335.exe
AMD Graphics http://www2.ati.com/drivers/beta/amd_catalyst_13.11_mobility_betav1.exe (if you have AMD graphics driver)
For NVIDIA drivers please check this link
7. Now everything will work perfectly in your new Windows 8.1, So ENJOY!!