Of course you don't expect to win a lottery. What do you say?

If I win a lottery, I will buy myself a house.

If I won a lottery I would buy myself a house.

If I would win a lottery, I would buy myself a house

You're not going to sell your car because it has a sentimental value.

If I sell my car, I will feel bad.

If I sold my car, I would feel bad

If I would sell my car, I felt bad.

Your helped your friend once. Now they don't want to help you and you feel betrayed. You want to remind them, that you helped them. You say:

If you needed help, I would help you.

If you needed help, I was there for you.

If you had needed help, I would've helped you.

You took an exam. It didn't go well for sure. You think you failed it.

If I failed the exam, I would give up the course.

If I've failed the exam, I will give up the course.

If I fail the exam, I will give up the course.

You don't expect fire in your school. You ask your friend:

What would you do, if there was fire in the building?

What will you do if there's fire in the building?

What woud you have done, if there had been fire in the building?

Somebody asks you in the street: "Excuse me, where is the bank?" You answer:

If you go straight, you'll see it on the right.

If you went straight, you'd see it on the right

If you'd gone straight, you would've seen it on the right.

Your friend has an exam tomorrow. You are sure they will fail, if they don't study. You say:

It's high time you start to learn for the exam.

It's high time you started to learn for the exam.

It's high time you had learnt for the exam.

You didn't go to the protest because you were tired. Then you stayed at home and feel FOMO. You think:

I wish I went to the protest.

I wish I had gone to the protest.

I wish I would have gone to the protest.

Your feel down and you need your friend not to leave you. You say:

I'd rather you have stayed with me.

I'd rather you stayed with me.

I'd rather you stay with me.

A month ago, you were angry at your friend, but didn't say anything. Now, your conflict escalates and you regret not solving the problem at the very beginning.

If you talked to them earlier, it would be better.

It would be better, if you've talked to them earlier.

It would've been better, if you had talked to them.