Laptop Issues

Hi,
I have a laptop and i was listening the music and the music pauses sometime like the laptop processor is running slow. Two days ago I was listening to music on the laptop using headphones and then I removed my headphones. The laptop then switched to loudspeakers but as soon as it switched to loud speaker the speaker as If just froze or got stuck and the laptop was making a big hardware noise through the speakers. The noise kept on going. This is a familiar sound when a music player just stops playing sound for a few split seconds because or slow hardware. But this time the speaker was making loud non stop then I had to manually shut down the button. Since then my laptop is stuck and cannot do simple tasks like opening file and normal computer use. It responds after a few seconds. Another unusual thing is that I have windows 8 and when iam trying transfer some files to a usb the speed is very unusual. In one second the transferring speed is 3mbps then the speed slowly goes down to 0bytes after two seconds. And this happens all the time. And it goes up and down. The sound of the processor is also unusual, it doesn't make much noise anymore and I make a low processing sound every few seconds.

I was trying to install another operating system but There is another problem I have bought this laptop from a person and the motherboard or the bios is locked with the administration password. He gave me the password for administration. And I enter it whenever I turn on the computer before the windows loads up. How can I remove this.