My keyboard on my Surface Laptop 1 stopped working after an update too.
I went to device manager (by typing devices in search bar) and found the HID Mini Driver had an error.
I tried updating, as others suggested, but it said that I had the most current driver.
I simply uninstalled the driver and then told it to detect new hardware. Keyboard started working again.
I hope this helps someone else out.
This seems like quite a mess.