To say no about the past, use didn't and the plain verb. The didn't already shows the past, so the verb goes back to plain.
didn't + base verb
She worked. → She didn't work.
I went. → I didn't go.
They saw it. → They didn't see it.
Not "I didn't went." — say "I didn't go.". The past is already inside didn't, so the verb goes back to plain: go, not went.
Try it: She ___ to work yesterday. (didn't go / didn't went / didn't goed) Answer: didn't go — After didn't, the verb goes back to plain: didn't go. "went" and "goed" both try to mark the past again, but didn't already does that.
Did + base verb (asking)
To ask about the past, put Did at the front and use the plain verb. Same idea: Did carries the past, so the verb stays plain.
She worked here. → Did she work here?
You went out. → Did you go out?
They saw you. → Did they see you?
Not "Did you went out?" — say "Did you go out?". Did already shows the past, so the verb goes back to plain: go, not went.
Try it: Mei went to the party. Ask if Mei went to the party. Answer: Did Mei go to the party? — Start with Did, then the person, then the plain verb: Did Mei go to the party? Leave "went" out. Did already carries the past, so the verb goes back to go.
Try it: Lars saw the email. Ask if Lars saw the email. Answer: Did Lars see the email? — Did goes first, then Lars, then the plain verb: Did Lars see the email? Leave "saw" out. The past is already in Did, so the verb is see.
Short answers: Yes, I did
To answer a Did question, use did on its own, not the main verb: Yes, I did. / No, I didn't.
Did you go? → Yes, I did.
Did she call? → No, she didn't.
Did they win? → Yes, they did.
Not "Did you go? → Yes, I went." — say "Did you go? → Yes, I did.". Answer with the question's word (did), not the main verb.
Try it: Did Mei enjoy the trip? → Yes, she ___. (did / does / enjoyed) Answer: did — The question used Did (the past), so the answer matches it: Yes, she did (not "does" and not the main verb).
Try it: ___ you like the movie last night? (Did / Do / Was) Answer: Did — "Last night" is the past, so start with Did. "Do" asks about now, and "Was" does not go before an action word like "like".
Try it: Remember where the past lives. He didn't ___ me. (see / saw / seen) Answer: see — The past is inside didn't, so the verb goes back to plain: didn't see. (After Did or didn't, always the base verb.)