Desktop Operating Systems and Recovery

My desktop PC will not wake from sleep mode as of yesterday. I tried turning it off with the power button and then turning it back on. The power comes on, the fan runs (I can't hear it but I can feel a very light flow of air coming from the exhaust vent), but the monitors seem to stay asleep. The PC power light is on, but after the initial sound that normally occurs when hitting the power button, the PC stays quiet like it's in sleep mode. It doesn't sound like it's booting up or anything. After a few times trying this, unplugging and replugging everything back in, I noticed that the keyboard and mouse don't appear to be getting any power. They plug in to the USB outlets in the back. It's the HP keyboard and mouse that came with the computer. 

I have a WD backup drive that I keep plugged in to one of the USB outlets on the front of the PC. That device appears to be running when plugged in... at least the light is on. But when I plug the keyboard or mouse into that same USB outlet, nothing happens. No lights come on and they still don't work. 

I look at all the suggestions on here about dealing with PCs that stay in sleep mode and I can't follow any of them because I can't ever get anything to appear on a monitor and the keyboard and mouse don't do anything. All I can do is turn the PC on and off, but that doesn't lead to any solution. It appears to stay in sleep mode even when I do that, since nothing ever comes up on the monitors (I have a dual graphics card and two monitors - neither of them does anything now). The monitor appear to be on and working... just not getting anything information or instructions from the PC I guess. If I turn them on and off they give me the normal messages that are generated just by the monitors themselves. I took the panel off and blew out all of the dust and everything appears to be intact. I had some kind of problem booting up last week and that appeared to be fixed by doing a system restore to the last point available. It ran fine for a day or two after that, and then yesterday I couldn't get it to wake from sleep mode. Thanks in advance for any help.