I didn't know about the concert so I didn't go to it.
If I had known about the concert, I would have gone to it.
My commute is very long and difficult because I have to change trains. (shorter and easier)
My commute would be shorter and easier if I didn't have to change trains.
The historical building was demolished because there was a fire.
The historical building wouldn't have been demolished if there hadn't been a fire.
The council decided not to convert the building into a civic centre, so teenagers have nowhere to go. (somewhere)
If the council had decided to convert the building into a civic centre, teenagers would have somewhere to go.
I don't have enough money to open a restaurant.
If I had enough money, I would open a restaurant.
There's no funding so the subway line couldn't be extended.
If there was funding, the subway line could have been extended.
It's easy to shop online because we have debit and credit cards. (difficult)
It would be difficult to shop online if we didn't have debit and credit cards.
I'm in a bad mood because I didn't have my coffee this morning.
I wouldn't be in (such) a bad mood if I'd had my coffee this morning.