my cpu turns on green light turn on but red light doesn't turn on no beeps monitor showing no signal input power saving mode

What is this "green light" "red light" that you are talking about? Need details about the issue, when did it start, what did you try if anything already? This can be either a dead power supply, motherboard or video card. Please post the computer brand and model, is there an add-on video card or just onboard?

You can try to reset the BIOS to defaults, at times that can clear up boot issues.