\documentclass{book}
\usepackage{pgffor}

\newcommand\InsertBlankPages[1]{% \InsertBlankPages{n} => insert n blank pages
	\foreach \blank in {1,...,#1} {
		\newpage
		\thispagestyle{plain}
		\mbox{}
	}%
}

\usepackage{xepersian}
\settextfont{Yas}

\begin{document}
\pagenumbering{alph}	
\pagestyle{plain}
\InsertBlankPages{28}
%\InsertBlankPages{29}
%\InsertBlankPages{32}	
\end{document}