The keyboard doesn't work but the touchpad still does, right? On the lower right by the virtual on/off button, one of your choices is to activate the virtual on screen keyboard. Then using the touchscreen or touchpad, you can search for device manager and it'll come up.
I've quit using the device manager for this problem. I've had much better results by unplugging from the power and holding the physical on/off key until the machine restarts.