had,would have

[gulrina]

i m a bit confuse which 1 is correct,

1)if i had a car,i would'nt have gone by bus.
2)if i had a car,i would have'nt gone by bus.
3)if i had a car,i would'nt have been gone by bus.
4)if i had a car,i would have'nt been gone by bus.

[Casiopea]

The first sentence is correct:

1) If I had a car, I wouldn't have gone by bus.

The second sentence is incorrect. Negative "not" (contracted form -n't) must attach itself to the first auxiliary verb, not to the second auxiliary verb, which is what we have here:

2) If I had a car, I would haven't gone by bus.

The third sentence is also incorrect. There can only be one past participle per verb phrase. Below we have two:

3) If I had a car, I wouldn't have been gone by bus.

The fourth sentence is also incorrect. Negative -n't is attached to the wrong auxiliary verb, and there are two many past participles:

4) If I had a car, I would haven't been gone by bus.

The correct form: -n't attaches to "would", the first auxiliary verb, and "wouldn't" goes with the past participle "gone":

1) If I had a car, I wouldn't have gone by bus.

Please Note
i. Capitalize "I".
ii. Contracted "not" looks like this, -n't, not like this, -'nt.

All the best.

[gulrina]

thank u so much casiopea,
i really appreciated your guidance.I will strickly fallow this next time.

[Casiopea]

You're most welcome.