'Did' is the only helping verb for the simple past. We use it for questions, and we use 'didn't' for negatives. For positive sentences, we don't use a helping verb.

Well, if your sentence is in active-voice, use 'DID' (For Negative and Interrogative sentences, not for Affirmative sentences [- use V-2 form]). 1) I went home. 2) I didn't go home. 3) Did I go home ? And if it's in passive-voice, use 'WAS' (For Affirmative, Negative and Interrogative sentences. Use 3'rd verb form for all sentences.). 1) I was punished by dad. 2) He was not surprised by his entrance. 3) Was she also loved by him ?