Don't is a contraction of do not. Avoid such illiteracies as "he don't," "they don't got," and "if don't seem." Do is a verb in the present tense and is never used in the third-person singular; use does. Don't think, a familiar, widely used expression, is not wholly logical. When one says "I don't think I want to leave," what he is really saying is that he does think that he doesn't want to leave or he thinks that he wants to stay. Don't think is not ungrammatical, but it is a wordy, careless expression.
Dictionary of problem words and expressions. Harry Shaw. 1975.