@akbar122 A little more information would be helpful. Although I agree with @geirandersen that the battery is likely at fault, I would recommend checking a few other things before replacing it.
First, does your AC adapter power the computer at all? Does it turn on when plugged in? If not, you should verify that your power supply is outputting the correct voltage. You'll need a voltmeter for that; the rated output is 19.5V and that's what you should see at the power jack.
Once we know where you're at with the power on situation and whether or not your AC power adapter is working, we can figure out what your next steps should be.