I just built a new computer for myself and it was running fine for about a month and then one day I go to power it up and the light on the monitor turns green for a second and then it goes into sleep mode (amber color light). I have an optical mouse and that lights up, but the lock lights on the keyboard won't light up. The next day I went to boot it and the computer itself wouldn't even turn on. So I thought it was the power supply so I got a new power supply and now it turns on, but its doing the same thing with the monitor and keyboard. If anyone could help me out I'd appreciate it.

Are you getting any beep codes? Do the lights on the keyboard flash when you power-up? The keyboard lights are a good indicator, since that is what happens when the KB gets a reset pulse. This, in turn, indicates that the computer is initializing, at least. No KB flash or beep codes indicates likely bad CPU chip (possibly damaged by original power supply).