I have toshiba touchscreen with windows 8 and when it went through a "critical" update on May 23 the mouse and keyboard stopped working once restarted. Because it is touch screen I can do a system restore back to the last update. This makes everything work again but a few days later when the update is required, it causes both mouse and keyboard to stop working. I saw a previous post about something like this and having to hit windows + w but with the touch screen keyboard I can't do that.

Try to run Hardware Troubleshooter. It checks for common issues and makes sure that any new device or hardware attached to your computer was installed correctly.

a. Press Windows Logo Key+X then click on Search screen.

b. Type “Troubleshooting” without quotes and click on Troubleshooting.

c. In the new window, click View all on the left pane.

d. In the list of options, click on Hardware and devices.

e. Click Next and follow the on-screen instructions.

If issue persists, then try Clean Boot. This helps eliminate software conflicts that occur when you install a program or an update or when you run a program in Windows. It starts Windows by using a minimal set of drivers and startup programs. How to perform a Clean Boot in Windows:

http://support.microsoft.com/kb/929135

Note: After troubleshooting, refer to this section "How to reset the computer to start normally after clean boot troubleshooting" in the above link.