Computer Shuts Down Randomly

So, my friend was playing an online game (Howrse.com), and this has happened to her several times. It never happens to me while i'm on my computer. I don't play games on my computer. My computer will just shut down randomly. The monitors will go black, but the PC never reboots. It will stay on though. I will have to manually turn it off, then turn it back on. What can I do to check and see if my components are good? They should be. They are like 2.5 years old. I bought all of them at the same time.

Well as a check, Go to power settings and turn off fast boot. Set the screen to turn off to "never".(on power)
Turn off Hibernation. Reboot and see if that fixes it . You can re-enable them one at a time to see which
(one or more) may be causing it.
Update the video drivers as well.
Can't Turm off Fast Boot and/or Hibernation(?)

Turn On or Off Fast Startup in Windows 10

Are you sure it's not just a display/graphics-related issue? I.e. could Windows still be running otherwise.. you could try leaving Cortana on to respond to voice, and check if there's any response.

Also see (e.g.)
What causes a computer screen to randomly go black while the CPU and monitor is powered on? - Quora
Screen goes black at very random times, PC still running. | Tom's Hardware Forum
https://answers.microsoft.com/en-us/windows/forum/all/random-black-screen/d34981ca-4306-4c93-8052-6a4268138e91

Is your BIOS up to date?

Lots more if you search for
screen suddenly goes dark at random

Try leaving it in Safe Mode for 'long enough'. If it still happens randomly most likely to be a hardware issue.

Some other basic things:
Enable and Disable Driver Verifier in Windows 10
MemTest86+ - Test RAM
HD Tune (free) Health and Error scan tabs - to check your disk