Lesson 29: か and も as modifying question nouns (note なんと なんて なんか)
When か isn't marking a question, it can turn interrogatives into generic nouns.
なにか something
だれか someone
どれか "somewhich" (metaphorically; as in one of the options)
いつか sometime (sometimes "in due time"/"eventually", like in english)
なにかあった？ Did something happen? (NOT "what happened?")
When も isn't marking grammatical inclusion, it can turn interrogatives into "in/exclusive" nouns. This is more complicated, and aside from だれも they can only be used with negatively "oriented" phrases. (* orientedness: see footnote)
なにも anything/nothing
だれも everyone/anyone/noone
どれも any of them/none of them
いつも anytime/never
誰もいないか？
どれか and どれも are noticeably less common than the others due to the logical nature of どれ.
The fact that だれも can be used for "everyone" in positive statements is irregular, and every other interrogative has its own irregular "every X", but I can't be bothered to cover them.
There's an obvious logical distinction between "every particular thing" and "any one particular thing". By attaching でも, you give it "any" in the sense of "any one particular thing", and it can be used with positive statements.
私が誰でも助ける I'll save anyone.
With that out of the way, let's look at なんか, which comes from なにか. In practice, なんか is one of the most common filler words in japanese, and is frequently used in places where translations should use "sorta", "like", etc. なんか can still mean "something", but this filler use is too important to ignore.
なんか変！ That's like, weird!
On the topic of なに-based grammatical terms, なんて is frequently used to express belittlement or scorn. なんて isn't always negative, it's a matter of nuance. なんと is used the same way but does not have the negative nuance.
なんて優しい。 How sweet.
なんと優しい。 How kind. (not sarcastic)