Blood test shows 0 monocytes. all other components of bloods are in range except monocyte. slightly raised in eosinophil. what happen if monocyte o ?

Bad result: There's no disease in which the monocytes disappear selectively and you're not obviously seriously sick. If your blood was sent to an old-fashioned lab in which 100 cells were counted, there might not have been a monocyte among them by dumb luck. Or a counting machine may have been run improperly. I'd also ignore any white count that's 'slightly raised' if you feel well.