何の話だ

what are we talking about?

→ 何
phrase Uncommon #11,420
what are we talking about? Used to ask what the current topic is. In casual speech, it can also express confusion about what someone means.
JA: そういえば、何の話だっけ?
EN: By the way, what were we talking about again?

何の話だかさっぱり分かんないよ。

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

いったい何の話だよ?

What on earth are you talking about?

何の話だ

What are you talking about?

— マルコムX (1992)

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?

What are you talking about?

— 暗殺の森 (1971)

いったい何の話だ…

What on earth are you talking about…

— 続・夕陽のガンマン (1966)

それは何の話だ

What are you talking about?

— マルコムX (1992)

いったい何の話だ?

What on earth are you talking about?

— ドライヴ (2011)

外見じゃなく何の話だ?

What are you talking about—not my appearance?

— GHOST IN THE SHELL (1995)

何の話だレストランか?

What are you talking about? A restaurant?

— グッドフェローズ (1990)

何の話だ?

What are you talking about?

— ムーラン・ルージュ (2001)