Try restarting the laptop. It is possible that the keyboard glitched or the display froze.
Have you recently done any repair work or upgrades to the computer? I have done many repairs on laptops and in all honesty, I have had a few instances where I forgot to plug a few connections back in, resulting in said device not working.
Has there been any water damage? Keyboards are the most vulnerable to water damage, and may need replaced.
If you're tech savvy and good with a screwdriver, I recommend opening the computer up and checking the keyboard cable to make sure it's not unplugged or damaged.