i do the following steps to test phpbb 3.0.B3
1- install phpbb 3.0.B3
2- register some users in Arabic & English
3- write some posts in Arabic & English
everything is well and the arabic words is shown until I do the follwing:
4- login to the ACP
5- made a full database backup
6- restore this backup

after that i can't read any arabic word / username and every arabic character is replaced by '?' so the username shown like '???????'