To start with it was not a cartoon, it was a movie about a unicorn that is lost and this boy is trying to find him in this big castle that has a devil like creature in it I'm not exactly sure what happens in it but I do remember I big devil like creature that has stolen or tricked the unicorn in to going to his castle, and the boy needs to save him for some reason. I do remember it being very fairytale like and quite scary in parts for a young child, however I still enjoyed it and ever so often I get little flashes of it in my head with makes me really want to see it again.

If any one has any idea it would be extremely helpful thank you.

One of the Unico (http://en.wikipedia.org/wiki/Unico) movies maybe.

Thank you for responding but I did have brief look at some pictures that I assume were unico, and they all looked animated to me and unfortunately its not an animated film. Thanks again though for the input.

Legend (http://www.imdb.com/title/tt0089469/)?

Sounds like legend, one of Tom Curise's first movies.

Thank you both for suggesting legend. It just so happens that I put that on my dvd rental list and it came through this morning, and it is the same movie!! Finally, thanks again.