Use does when your subject is he, she, it or one singular noun: Does she work here? Use do with I, you, we, they or plurals: Do they know?
In questions and negatives, the main verb stays in its base form after the helper: Does he live nearby?, We don't go on Sundays. It's only do or does that changes, never the verb behind it.
Grouped by the subject you're writing about
Writing about him, her or it? Start the question with does. Does she work here? Change only the subject to a plural, and the helper shifts too: Do they work here?
The same subject that takes does also takes doesn't in a negative. Does he drive to work? He doesn't drive to work. Notice the main verb stays bare: Does he live nearby?, not Does he lives nearby?
Writing about you, we, they or a plural noun? Use do to ask. Do your friends know? Compare with a singular friend: Does your friend know?
The you/we/they side of negatives uses don't. Do they sell stamps here? They don't sell stamps here. Again the verb stays in base form after the helper: We don't go on Sundays.
The same subject grouping decides the helper in both questions and negatives. Where does he live? asks about one person, and He doesn't live here agrees with that same singular subject. Where do they live? asks about more than one, matching They don't live here.
To check your own sentence, find the subject first. If it's he, she, it or one singular noun, choose does or doesn't. For I, you, we, they and plurals, choose do or don't, then follow it with the base form of the verb.
In questions and negatives, only the helper changes with the subject; the main verb never takes the -s ending there. Does or do is the word that shifts to match who you're talking about, so the verb behind it stays in its base form: Does she live in Leeds?, not Does she lives in Leeds?
The same holds in a negative, where the order is subject plus do or does, then not, then the base verb. My neighbours don't own a car sounds right because own carries no ending; don't owns is the mistake even fluent writers make when they're concentrating on the subject.
A quick self-check: read your main verb aloud. If you hear an -s on it after do or does, drop it, as in Does he arrive early?