You have to be a little more specific than that?
For that question, the way you have asked it, I can ask you another question which is
Did you switch on the computer?
Is the monitors power cable connected to the Power socket and powered on?
Is the Monitors VGA cable connected to the On-board VGA card or a Graphics Adapter which is in a Slot on the board?
Is your keyboard connected to the computer?
Is it detected during boot?