So I've had this computer for over 7 months and it has been flawless. Yesterday, before I went to bed, I was on my computer and it just froze - my keyboard and mouse and all USB ports stopped working (my music kept playing). I shut it down, and got the error message on the first page as the Bios loads "Keyboard not detected", and at the bottom the usual "Press f1 to continue." So I press f1. No, just kidding.
 
My computer won't boot because it won't recognize my keyboard. I've tried different keyboards, I've tried different ports (including the ones directly on the motherboard and ones in front). I've tried USB3 and USB2. I've looked inside the computer to see if anything was unplugged or something like that, and it looks fine (and, as I mentioned, it doesn't work even when plugged directly into the motherboard). What could have happened? I really don't want to get this replaced.. that's such a hassle. 

ok, you have had the computer for over 7 months and it has been flawless; So SOMETHING HAS CHANGED., now try a restore point if you have saved one to eliminant possible drivers, and address conflicts then Bios reset, to eliminate corrupt settings, next easiest is PSU, You can try disabeling key board detect in BIOS. to see if that works.