When something breaks down, it stops working.
EG: The machine broke down yesterday and we had to call someone to fix it.
When you break into a place, you enter this place illegally; without permission.
EG: A thief broke into his house yesterday but the police came in time and arrested him.
When you bring along someone, you get another person to join you.
EG: Can I bring along a friend to the party tonight?
When you bring up something (usually a subject, an idea, a topic), you raise it in order to start a conversation.
EG: He brought up the subject of marriage again but she didn’t want to talk about it.
When you bring something back, you return it.
EG: If you borrow a book from the library, you must bring it back.