Hello aspirant,

Hope you are doing well!!

I Had and accident yesterday.

We use the second form of have because it is the past perfect tense. I the sentence yesterday is use in last so, from yesterday we determine that it is the past perfect tense. so, we use had in place of have. Have is used for present tense and we are talking about past perfect tense so we use had.

I hope you understand.

Fell free to ask any query.