Did you actually remove the cooler from the CPU? Everyone jumped to the conclusion you need thermal paste, but all I got from your post is that you dusted your PC off with toilet paper, and blew on it.
Sorry I know this is serious, but its too funny. And if you didn't remove the cooler from the CPU then you don't need thermal paste (right now, but you should replace it). Even so your PC would still post without thermal paste, the CPU would get pretty toasty, but if anything it would post and then shut off to protect itself from overheating.
What I understand is your PC turns on, but your peripherals don't work. I would just switch off the power supply, unplug & plug everything back in and see if that fixes it. But really we have very limited information like, did you unplug anything from the motherboard? Were your mouse and keyboard plugged into the IO panned or the front panel? There are several variables.