Thanks for your replay
No , not only course name but also the users name and every table have an Arabic characters.
These Courses was manually created.
As far as I know, that is not repairable. I suggest to install a new Moodle from scratch on that machine and check if all works fine, and then restore your database from a known good backup.
It would be interesting to know how it ended up like that.
Thanks Koen for your interest, I knew where was the problem.
It was in the database, and i am lucky to found my latest backup. the proplem solved with restoring that backup.
but i still don't know why it got like this.