UK:*UK and possibly other pronunciationsUK and possibly other pronunciations/ˈhæpən/US:USA pronunciation: IPA and respellingUSA pronuncation: IPA/ˈhæpən/ ,USA pronunciation: respelling(hapən)

WordReference Collins English Usage © 2020
When something happens, it takes place without being planned.
Then a strange thing happened.
There'll be an investigation into what happened and why.
Be careful
Happen does not have a passive form. Don't say, for example, ‘Then a strange thing was happened’.
‘take place’, ‘occur’
Happen is usually used after vague words like something, thing, what, or this. After words with a more precise meaning, you usually use take place or occur.
The incident had taken place many years ago.
Mrs Brogan was in the house when the explosion occurred.
Don't say that a planned event ‘happens’. Say that it takes place.
The first meeting of the committee took place on 9 January.
The election will take place in June.
‘happen to’
When something happens to someone or something, it takes place and affects them.
I wonder what 's happened to Jeremy?
If anything happens to the car, you'll have to pay for it.
In sentences like these, don't use any preposition except to after happen.
You use happen in front of a to-infinitive to show that something happens or exists by chance. For example, instead of saying ‘The two people he wanted to speak to lived in the same street’, you can say ‘The two people he wanted to speak to happened to live in the same street’.
I just happened to be in the wrong place at the wrong time.
If you happen to see Jane, ask her to call me.
You often use happen to be in sentences beginning with there. For example, instead of saying ‘A post office happened to be in the next street’, you say ‘There happened to be a post office in the next street’.
There happened to be a policeman on the corner, so I asked him the way.
Be careful
In sentences like these you must use there. Don't say, for example, ‘Happened to be a post office in the next street’.
'happen' also found in these entries:

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