Compaq Presario CQ42 notebook will not turn on

Dear Everyone,
A few days ago my computer cannot be turned on. The hard drive light indicator will flash for several seconds then will stop for several seconds and will flash again. The process start over and over again but the screen is black. The disc player at the side will blink at the same time and stop at the same time the hard drive light indicator disappears. If I will remove the battery from the computer and press the power button the indicator lights of the computer will just blink in just a fraction of a second and disappear.
Is anyone can tell me what is going on with my computer? Thanks