I am not a native English speaking person. My native language is Russian.
For almost half of my life, I enjoy English speaking environment.

It is handy to keep in mind series of words directly corresponding to each other.
Say, English WH question words have simple direct Russian translations:

English	Russian	transcription
what	что	chto
what...for	зачем	zachem
when	когда	kogda
where	где	gde
which	который, какой	kotoryj, kakoj
who	кто	kto
whose	чей	chej
why	почему	pochemy
how	как	kak

If I do not know an answer to a question
and do not like to go into details (say, because they are irrelevant),
I can reply by a single word.
In Russian, you just add a tiny suffix "-то" to the question word:

Question word	Indefinite word
что	что-то
зачем	зачем-то
когда	когда-то
где	где-то
кто	кто-то
чей	чей-то
как	как-то
почему	почему-то

Let us try to translate this table.

English question word	Indefinite word
what	somewhat
what ... for	somewhat ... for
when	sometime
where	somewhere
who	someone, somebody
whose	someone's
how	somehow
why	???

In most cases, the indefinite word is formed by adding the prefix some to the question word.
Sometimes the question word is replaced by an appropriate noun:
For example, when is transformed to sometime,
rather than to somewhen.

But what to do with why? I really don't know!

In English there is no word somewhy.
But there is no any other word which could be used instead.
I desperately miss it!

I mean a precise replacement.
"For some reason" is not acceptable,
because "why" may refer not only to a reason, but also to a cause, accident, or whatever.

Really, I would appreciate any solution of this riddle.
Or explanation, why there is no solution.

Somewhy ?