Dell Inspiron 15R N5110 :: Not Switching On

when I tried to play any sound (details at bottom ). Anyway, I went onto the dell website to get a driver to see if it would fix it. I had to fond this service key thing, and then it told me I needed to get these three things. They were a couple of number with a letter or two in there, meant nothing to me. So I installed one, and it came up with this grid, and the boxes were getting filled in, and then some of the, were red in the middle. My laptop was reeeaaally loud at this point. But then, the power cable went out, and I've had this problem where the laptop loses connection to battery, and it went. So then, my laptop went off. And now when I tried to switch it back on, what happens is the power button lights up, three buttons on the right light up momentarily. But the screen stays black. So then the only things indicating it's 'on' is the power button, and the three lights on the bottom of the laptop, which I have no idea of purpose. Also, my laptop is very very quiet at this point. Anyway, yeah, I've taken battery out, charger out, both out, left both out, put both in, that hasn't solved it. 

I had been messing around with my playback devices (enabling/disabling) because I had tried using Skype. Originally, I had a problem where my skype calls were coming through my headphones (plugged into the headphone jack), but any other noise, coming through my laptop speakers. I sorted this by disabling my "communications headphones". And then now, I had a problem where I was in a skype call, when everything else stopped producing sound, bar the skype call. So I tried reopening my browser, but nothing, checked iTunes, and the music wasn't playing. So I thought it may have been the skype call. It wasn't, as I ended it, and still no noise was coming through. Then after a few minutes, there was a just this background noise coming through my headphones, like a fan. I noticed that it was coming out of my headphones when plugged in, but also my speakers when unplugged. Also, when I muted sound, the noise stopped, so I thought that may hint at where this problem may occur.