What do you mean by "sentence pattern"? Do you mean change the word order or grammatic structure of a sentence? If so, it's very unlikely that such a program exists, because English is a rather irregular language, and doing things like that with any degree of consistency is a fairly complex task. Things like MS Word can't even CHECK your grammar very well, compared to a human being, let alone create new structures from existing sentences. That's not something computers are good at.