I want to create two single.php templates, one for English language and the other one for Persian language, because post in English is too different according the post in Persian, because of the css direction need.
For this propose I've created two single.php templates, but everytime the English one opens.
Now, how do I send the post to the other one which is Persian single.php.
I think you have to make two categories first. Sorry my English is very bad, if my answer is a little bit understandable (:D).
Create 3 files for the single page: single.php, singleEnglish.php, singlePersian.php, then add this code in single.php:
<?php
$post = $wp_query->post;
if (in_category('tag_id Persian') ) {include(TEMPLATEPATH . '/singlePersian.php');}
else {include(TEMPLATEPATH . '/singleEnglish.php');
}?>
Example can be found here. Single page is different for Products and Blog.
You can't run two single.php for the same post type. The template hierarchy doesn't allow that.
You need to look into rtl support for your site. It is extensively covered in the codex. You can also have a look at the bundled themes to get a basic idea of how to do this.
The other means might be is to use get_locale() to split you single.php
Example: (Please note, I'm using Afrikaans as the locale to check, change this to Persian)
if( 'af_AF' == get_locale()){
// Do something for Afrikaans language
}else{
// Do something else for other languages
}