We fixed it. Thanks you Nick.
**SOLUTION: There was a comment line in function.php as before <?php line. I moved the comment line under the <?php as //blabla. Sorry it was complately my fault 
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Detailed: I don’t have any plugin. actually my main purpose is creating a plugin-free theme.
Now. I deleted my local site. And i exported my theme before that. I created same domain again. I copied my theme files again and activated it. It does again. I can’t see my medias. When i switch theme to twenty-five it works well.
While I type these reply, i was trying whatever i think.
I deleted half of the theme files until it works well. So it solved when i deleted function.php. I was thinking about comment line was html. I knew something is wrong with that. Actually i am not a webdesigner. So I’m sorry to bother you and take up your time.
Take care.