@devika14103 checked the power supply by disconencting the power supply from the motherboard. Then place a jumpoer between the green wire and a black ground wire. Since we do not know exactly what power supply plug you have, it will help if you post a picture of it with your Question. We can then show you where to place the jumper. [guide|21499]
If it does not work, you know you have a bad power supply. If it does work you need to check the power button as well as the motherboard.