Trying to download a driver...

Ok, I have no clue what I'm doing, so (obviously) I need some help!  A couple of weeks ago, I had the brilliant idea of "cleaning up" my computer myself (instead of having a professional do it) and apparently deleted something that is needed for my speakers to play. 

Just to answer the obvious questions:

 I HAVE shut down and restarted my computer.

It is NOT on mute.

I've tried "install new hardware" and it says it does not detect any hardware (I've checked multiple times and the speakers are plugged in correctly).

The speakers definitely DO work (tried them on the laptop and they work just fine). 

So I had someone suggest coming here and downloading a driver (or something like that - really don't know all the technical lingo).  I was using the "Downloading and Installing drivers using the Dell Download Manager" page (link: http://support.dell.com/support/topics/global.aspx/support/kcs/document?c=us&cs=04&docid=266471&l=en&s=bsd)  Step #12 is where I get stuck.  It says I'm supposed to doubleclick the download file.  Well, when I do that, it wants me to pick a program that I want to use to open the file and none of them work.  Supposedly a small window is supposed to appear with the "continue" and "exit" buttons and I'm supposed to click "continue."  (This is step #13.)  I can't get beyond this step, because I do NOT have those options. 

Any ideas?  :)