Don't vs. Doesn't

To make a negative sentence in English we normally use Don't or Doesn't with all verbs EXCEPT To Be and Modal verbs (Can, might, should etc.).
Affirmative: You speak Spanish.
Negative: You don't speak Spanish.
You will see that we add don't between the subject and the verb. We use Don't when the subject is I, you, we or they.
Affirmative: He speaks Spanish.
Negative: He doesn't speak Spanish.
When the subject is he, she or it, we add doesn't between the subject and the verb to make a negative sentence. Notice that the letter S at the end of the verb in the affirmative sentence (because it is in third person) disappears in the negative sentence. We will see the reason why below.

Contractions

Don't = Do not
Doesn't = Does not
I don't like fish = I do not like fish.
There is no difference in meaning though we normally use contractions in spoken English.

Word Order of Negative Sentences

The following is the word order to construct a basic negative sentence in English in the Present Tense using Don't or Doesn't.

Subject	don't/doesn't	Verb*	The Rest of the sentence
I / you / we / they	don't	have / buy eat / like etc.	cereal for breakfast
he / she / it	doesn't

*Verb: The verb that goes here is the base form of the infinitive = The infinitive without TO before the verb. Instead of the infinitive To have it is just the have part.
Remember that the infinitive is the verb before it is conjugated (changed) and it begins with TO. For example: to have, to eat, to go, to live, to speak etc.
Examples of Negative Sentences with Don't and Doesn't:

• You don't speak Russian.
• John doesn't speak French.
• We don't have time for a quick drink.
• It doesn't rain much in summer.
• They don't want to come with us.
• She doesn't like meat.