Computer turns on, then nothing happens

When I went to go on my computer this morning I found that none of my peripherals were functioning, from the USB ports to my monitor. The monitor stubbornly said "No Signal", the light on my mouse was out, and strangely, the Numlock light was on on my keyboard, but wouldn't turn off.

I immediately forced my computer to power down, gave it a minute, and powered it back on, but the only thing that changed is that all 3 lights on my keyboard flashed and went dead. I also noticed that my PC didn't make its usual single beep upon power up.

Wondering if maybe it had just overheated overnight, I unplugged everything, took it outside, and gave it a dusting out. I then left it a few minutes to finish cooling off to be safe, hooked it back up, and hoped for the best. No such luck. Can anyone give me any ideas? This has not been the most pleasant morning.