The word "why": what's the difference between 为什么 and 怎么?
什么 = what

怎= how

怎么 = how / how is that (how come)

为什么 = for what = why

为什 is short form of 为什么

为何 is the literary form of 为什么

何故 or 何以 is the literary form of 什么原因 or 什么导致 (for what reason = why)


Examples:

&quot;什么我不能去？&quot; = &quot;What? I can't go?&quot; or &quot;what (you mean) I can't go&quot;
&quot;怎么我不能去?&quot; = &quot;How is that I can't go?&quot; or &quot; how (come) I can't go?&quot;
&quot;为什么我不能去?&quot; = &quot;For what (reason) I can't go?&quot; or &quot; why I can't go&quot;

Basically 为什么 (why) emphasizes the reason itself ; 怎么(how is that) emphasizes 'in what manner' or 'with what method'  the cause exist