I was having the same problem and here's my experience.
After poking at the Microsoft boards, other user found that on March 16, a Microsoft update pushed an updated Levano driver down to Toshibas. You can check your updates by going to the Windows/Start button and clicking on the settings. It's the gear/flower shaped icon above the power button. Click Update and Security and then Update History.
So in a nutshell, the wrong driver was installed. I saw two possible ways to fix it.
1) Open control panel. Type Keyboard into the search engine and pull up the keyboard properties. Say you want to change the properties. Go to the driver tab and select the option to roll back the driver.
This seemed like the most straight forward and safest option, but the Rollback button was grayed out on my computer, so I moved onto option 2
2) Find your Toshiba model number - mine is an L775 S7355. Google up your model number and driver. One of the first options should be the Toshiba page for your laptop. Select your operating system from the dropbox. I had a bit of a problem because Windows 10 wasn't on the list, so I decided to choose the operating system before I upgraded to Windows 10, which was Windows 7, 64 bit. The driver there was dated less than a year ago, so I was feeling pretty good about it.
When I tried to execute the driver, it wouldn't install because a newer driver (the one we want to get rid of) was already installed. It told me to uninstall this driver first.
This is where it gets risky, because once you uninstall the driver, the touchpad and keyboard may stop working all together and then you won't be able to get the new driver installed. So you need to have a back up prepared. If you have a touchscreen computer, you could turn on the onscreen keyboard. Otherwise you may need a usb keyboard and mouse.
Through Control Panel and Add/Remove programs, I uninstalled the Symantec Pointing Device. It required a restart. I did so and luckily the keyboard worked -- It looks like Windows picked a more generic driver. I didn't check at this point if the keyboard was working properly or not. I executed the Toshiba Driver that I had downloaded. The problem was fixed.