function change_admin_font() {
    echo '<style type="text/css">@font-face{font-family:"esfont";src:url("' . get_stylesheet_directory_uri() . '/font/esfont.ttf")}#wpwrap,#wpadminbar .ab-empty-item,#wpadminbar a.ab-item,#wpadminbar>#wp-toolbar span.ab-label,#wpadminbar>#wp-toolbar span.noticon,.rtl h1,.rtl h2,.rtl h3,.rtl h4,.rtl h5,.rtl h6,.media-toolbar-secondary,.media-frame.mode-grid .media-toolbar select,.details,.media-modal label{font-family:"esfont"}</style>';
}
add_action('admin_head', 'change_admin_font');