何の話だ

what are you talking about?

→ 何
phrase Uncommon #13,284
what are you talking about? A casual phrase used to question what someone means or to ask what the conversation was about. In the past-tense form 何の話だっけ, it means “what were we talking about again?”
JA: 急にどうしたの?何の話だ?
EN: What are you talking about all of a sudden?

何の話だ

What are you talking about?

— マルコムX (1992)

何の話だ

What are you talking about?

— ムーラン・ルージュ (2001)

いったい何の話だ

What on earth are you talking about?

— ドライヴ (2011)

何の話だ?

What are you talking about?

— 暗殺の森 (1971)

あなたを手術知ったのなら覚えてるはず何の話だ

If I learned about you through surgery... I should remember. What are you talking about?

— 嵐の中で (2018)

いったい何の話だ

What on earth are you talking about?

今度は何の話だ

What are you talking about this time?

— ア・フュー・グッドメン (1992)

何の話だレストラン

What are you talking about? A restaurant?

— グッドフェローズ (1990)

それは何の話だ

What are you talking about?

— マルコムX (1992)

何の話ださっぱり分かんないよ

I have absolutely no idea what you're talking about.

いったい何の話だ

What on earth are you talking about…

— 続・夕陽のガンマン (1966)