Let's start with some simple items.
It is the monitor itself that shows "no signal" being received from the computer. Can you connect the monitor to a different laptop or desktop, to confirm that the monitor is capable of receiving input?
Does your monitor have multiple inputs (VGA? DVI? HDMI? DisplayPort?). Have you used the OSD (On Screen Display) buttons on the edge of the monitor to cycle through each of those inputs, to find an "active" signal?
Turn the computer on, then press the "CAPS LOCK" or "NUM LOCK" keys on the keyboard. Most keyboards will have a lamp that lights up when you press either of these keys. If not, then the keyboard is not getting any electrical power from your computer.
If you have an external monitor attached to your desktop computer, try replacing the cable that connects the monitor to your computer.
Also, try replacing the monitor.
If you put your cheek near any of the air-exhaust areas on your computer, do you feel any warm air being pushed-out by the fans inside the computer (power-supply and/or extra fans)?
When you turn your computer on, do you hear the fans spinning?
Try removing the power-cord from your computer, and then press the on/off button for a few seconds, to completely "drain" any residual electrical power. Then reconnect the power-cord, and try again.