Native speakers often cut, that is, truncate some words that are clearly understood by other native speakers. 'Why'd you bring me here' is equal to 'Why did you bring me here?'. Some other common examples of this: Why'd ya do it? and, or Why'd ya do dat for? Please note: This is considered informal (and possibly substandard) English. If the 'd' is deleted the sentence can be understood, but that is missing the point: that is, how do native speakers actually talk? It is common to have some of that sound (which is not exactly a 'd' sound as in drain. 'Too complicated to mention here.') in speech and in informal writing.

'd means would. If you want to delete, you need to add "do" or "did".

What does the “‘d” mean here? The "d" 是“could or would ”的缩写。