wordpress apply filters and is singular()

You can try to remove the filter

remove_filter('the_content', 'some_func');

and add it again with your customized version of some_func() called some_func_mod():

add_filter('the_content', 'some_func_mod');

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)