Hey there! Sorry to hear you in this situation, also I am delighted that I am not alone. I am also Asus Z87 Deluxe MoBo use with 4770K. I also installed Win 8.1 last night and it worked all day. I restarted it and it restarted without keyboard and mouse.
On farther investigation, I figured out that I have no power on any USB ports. I tested it by connecting USB stick and see no light. I was advised to boot from DVD in Safe mode, go to device manager and uninstall USB driver. Then restart and it should install it again. To enter Safe mode we supposed to tap or press and hold F8. On my system it offers boot options- I can select DVD or SSD (it still detected). When press SSD, it goes on to load Win 8 up to the image- can not activate password screen without keyboard. Please, see my other thread on this forum, and if you find solution, please, post it here or to my thread. Here is useful link: http://answers.microsoft.com/en-us/windows/forum/windows_8-hardware/usb-ports-not-working-in-windows-8-after-automatic/23be4e2e-dbc4-423f-98c8-1add8680ceab
Here is my thread on IT Pro: http://social.technet.microsoft.com/Forums/windows/en-US/804eef49-7aa7-4248-b083-13b2cd999712/no-usb-after-windows-update?forum=winservergen
Here is my thread on Egg: http://www.eggxpert.com/forums/911966/ShowThread.aspx#911966
I hope that there will be an answer somewhere soon. Keep us posted!