If you have only Windows 8.1 installed on your pc, ry and hold down F8 or SHIFT F8 to load the advanced startup screen. It works sometimes and sometime it doesn't.
On the “Choose an option” screen, select Troubleshoot
On the “Troubleshoot” screen , select Advanced Options
On the “Advanced Options” screen , select Startup Settings
On the “Startup Settings” screen , select restart.
After the restart process Windows gives you the option to Enable Safe Mode
You can either perform a system restore if you have previously created a system restore point before the “faulty updates were installed” or you could manually uninstall the offending updates.
To Manually Uninstall Updates :
Go to Control Panel (you can simply search for it).
Got to Programs and Features
On the left, click View installed updates .
Select each of the recently installed updates and uninstall them.
Restart your PC and you should be back in business. You may have to restart a couple of times after the steps above before it finally gets past the “installing updates”.