起きたの

happened

→ 起きる
phrase Common #5,109
happened The の at the end can make this an explanatory question, often translated as “did it happen?” or, with 何が, “what happened?” 起きた can also mean “woke up” depending on context.
JA: 何が起きたの?
EN: What happened?

何が起きたの

What happened?

— バジュランギおじさんと、小さな迷子 (2015)

そこで何が起きたの

What happened there?

いつ起きたの

When did you wake up?

怖い事が起きたの

Something scary happened.

— サスペリア (1977)

今朝は何時に起きたの

What time did you wake up this morning?

信じれないことが起きたの

Something unbelievable happened.

もう寝たのにもう起きたの

You just went to bed, and you're already up?

一体何起きたのかな

I wonder what happened.

— 箪笥<たんす> (2003)

それは一体どうして起きたの

How on earth did that happen?

もう、もう起きたの

Already? You're up already?

ぼくが安全に保管するよ私が頼むまでそこで何が起きたの

I’ll keep it safe. What happened there before I asked?

— तुम्बाड (2018)