Asks 'how', 'why', 'in what way', or 'what kind of'. Commonly used conversationally as 'What's wrong?' or to ask how something should be done.
どうした？顔色が悪いけど大丈夫か。
What's wrong? You look pale — are you okay?
この問題、どうしたら解決できるだろうか。
How can we solve this problem?
どうした理由かは分からないが、彼の態度が変わった。
I don't know the reason why, but his attitude has changed.
子供が泣いていたので『どうしたの？』と声をかけた。
A child was crying, so I called out, 'What's wrong?'