error in language utf8

hi
I can migrate from joomla to wordpress successfully
but i have a problem
my articles ,users and my categories transfered very well but its show ?????????? means show (?).
my article language is persian-arabic and I set utf8 in setting but not working.
please help me to solve this problem
Thanks A lot

[No bumping, thank you. If the issue is that urgent, you may want to consider hiring someone.]