Here's where you can download your user guide.
You should be able to go there, put in your model, and download your manual. I don't know why not having bought your laptop new would keep you from doing that. Also have you looked on your hard drive? For the Dell & Toshiba computers I have I can click Start -> All Programs -> Dell or Toshiba and find the user guide there.
I would like to get an owners manual for my Acer Laptop. I can't get it from Acer because I didn't buy it new. Can anyone recommend a good free site?