Windows 7: New laptop, speakers not working with latest drivers installed?

Hi I recently bought a 2nd hand (4week old) acer e1 571. It originally had Win 8 installed, It is now running on Win 7 sp1 (afaik) with all the latest updates installed. This is why it has not just been brought back to the shop where it was purchased.
My problem is that I cannot play audio through the laptops own speakers. When in a very quiet room you can hear faint crackling from the speakers when they are turned up fully. If you plug in headphones or hdmi, the either will work perfectly no problem with sound. I have the latest Realtek audio driver for my computer installed and I have spent the last week checking and re checking all of the sound settings. The computer says that the device is ''working properly'' when I troubleshoot it. Im beginning to wonder are the speakers shot?

Maybe that was why it was originally brought back - the speakers didn't work? Did they work when you first got it? If not, I would take it back.

I was told they were working when the computer when it was bought. It was an unwanted gift that was bought for someone by the guy I got it off. I have been in contact with him regarding it already, I must get back to him about it.

make sure volume is turned up .
FN+F8 on my Acer

might have something to do with this to Windows 7[Afaik] if that means what i think it means