P0wer problem it sometimes on but after few second automatically off.and i think my laptop is having a virus

Overheating When the CPU overheats then it will shut down (i.e. thermal overload) and won't boot up again until it has cooled down. If this is the problem is not fixed then the CPU will eventually fail.
A faulty fan causes the problem or the fan and heat sink assembly are clogged with dust.
Check the CPU fan to see if it spins freely, if not replace the fan.
If the fan and heat sink is clogged with dust the remove the dust and make sure the vents are clear and dust free. Use a small brush and can of compressed air to do this.