Laptop does not work ocassionaly

Hello,

My Hp Compac laptop is 14 months old. Since last month it is having a problem. Sometimes When I press the power button the computer does not boot. Sometimes it works fine. You never know when it is not going to work. When it does not boot led at the num lock and caps lock blink 3 times. Again the next day when I start the laptop works fine..Kindly help me