The opposite of “do” is “do not,” usually contracted to “don’t.”

The opposite of “does” is “does not,” usually contracted to “doesn’t.”

“I do,’ “you do,’ “we do,’ “they do,’ “the birds do.’ “It does,’ “she does,’ “he does,’ “the flock does.’

So in standard English it’s “I don’t, “you don’t, “we don’t, “the birds don’t and “it doesn’t, “he “doesn’t, and “the flock doesn’t.”

But in many American dialects, “don’t” is used in contexts where “doesn’t” is standard: “she don’t drive,” “it don’t make no sense,” “the boss don’t treat us right.”

This is one of those patterns which is likely to make you sound less well educated and less sophisticated than standard English speakers. If you’re trying to shake off your dialect, learning when to use “doesn’t” is important.

You can usually tell when “doesn’t” is more appropriate by expanding the contracted form to two words: “does not.” It’s not “she do not appreciate my singing,” but “she does not appreciate it,” so it should be “she doesn’t appreciate it.”

But in popular song lyrics “don’t” prevails: “she don’t like the lights,” “he don’t love you like I love you,” “it don’t come easy.”