The past simple is used to express an action that is complete in the past. Usually the notion of time is present (in contrast with the present perfect). So we know when it has taken place.
Statement subject + verb - ed
Negative subject + did not (didn't) + verb
Interrogative did + subject + verb
Negative interrogative Didn't + subject + verb
I finished the project last week.
I did not finish the project last week.
Did you finish the project last week?
Didn't you finish the project last week?