I remember taking Spanish in 7th grade (my first year) and I remember the teacher making us all roll our R's as a class, to little avail. Some kids got it instantly, and a large group never did. I remember it feeling quite strange... the teacher made the sound and would ask us to imitate it, as if we should know how to make that sound from instinct! So I completely empathize with this problem.
I recently started taking an intro to Spanish course in college (forgot most of that stuff I learned in high school--to the extent that I ever really learned anything other than some words and phrases), and encountered my problem with rolling R's again. I picked up Rocket Spanish as a supplement to that, and because I really wanted to go beyond this class and actually learn the language (I'm half Latino myself, so I feel as if knowing Spanish would get me closer to my heritage).
It's been a few months and I'm still having a really hard time, especially with the words "carro" and "perro". "perro" is the worst! When I try to say it, it comes out sounding Middle Eastern with a "hack" like "Pe-hhhhhcckk-ro" :cry: Otherwise, I can make the Spanish R sound pretty well, I just can't roll it. The closest I can get to rolling an R (and only with certain words) is more in the back of my throat as if I was gargling. I know it's got to do with the tip of the tongue, and the roof of my mouth, but no matter how many times people tell me how they do it, I can't seem to understand what they mean, or imitate it, although it does feel at times as if I'm getting closer. I really wish there was a visual example showing the inside of the mouth and exactly what the tongue is doing, and whether or not to tense the jaw while doing it.
I looked online a lot for help and found some resources that didn't help me all too much (helped a little though), but may help you. The common suggestion to say "ladder" over and over doesn't help me at all, but some of the other information is at least good for guidance. Thing is: people who can do it, just do it. They don't think about it, and thus can't really explain (at least not in complete detail) HOW they do it. It's like explaining how to walk. You'd really have to explain just what muscles to flex and just how to keep balanced, something that is easier done than said (at least once you've already DONE it!)
Perhaps the fact I have a slight Long Island accent adds to the problem. I also have a large tongue relative to the size of my mouth, especially my upper jaw, which was under-developed when I was a teen and I needed orthodontic work to correct it. I'm wondering: is it possible to be physically incapable of trilling your R's correctly? Could some of us have the equivalent to a Spanish speech impediment?
*Here's the links that I promised:*