I had left my umbrella at work. I got soaking wet.
Is I hadn't left my umbrella at work, I wouldn't have got soaking wet.
Bill lost all his money. That's why he was in debt.
If Bill hadn't lost all his money, he wouldn't have been in debt.
I didn't have a day off yesterday because I had to finish my project.
If I hadn't had to finish my project, I would have had a day off yesterday.