Laptop keeps turning off

Hello,

I was wondering if someone can help me, last night i was typing on the internet, everytime i typed, other letters would come up also, the sign for the mute button would show on the screen and then the laptop would turn off. This happened about 3 times after another everytime I turned the laptop back on. Now when I try to turn on the computer, it loads to the welcome screen, i start to type in my password and then turns off. Sometimes it doesnt even turn on. Also the ac charger will not charge my laptop, no light is showing to charge. I have tried this also without the battery connected. The laptop will only attempt to turn on just by battery bower. I have a dell inspiron laptop. Can anyone help?! Please?!