誰か / どこか / 誰も / どこも【だれか / どこか / だれも / どこも】

か after だれ誰 or どこ makes "someone" and "somewhere". も after them, with a negative verb at the end, makes "no one" and "nowhere".

誰か or 誰も in a question

English asks "Is anyone there?" with "any", which pulls learners towards 誰も. A question about whether someone exists takes 誰か.

• × 誰もいますか → 誰かいますか

Particles around か and も

After か, particles follow as usual: だれか誰かに, どこかで. In speech, が and を are often left out.

も takes the place of が and を. Any other particle stays and も goes after it: だれ誰にも, だれ誰とも, どこにも. Going somewhere or being somewhere takes に, so "nowhere" is usually どこにも.

どこも with an affirmative verb

With an affirmative verb, どこも means "everywhere". "Everyone" is みんな in speech, or だれ誰もが in writing.

なんか何か and なん何も work the same way: "something" and, with a negative, "nothing". いつも is the exception: it means "always", with any verb.