character problem after upgrading php version to 4.4.2

[gtithesexy]

my site is western language and I'd no problem about my characters before upgrading php version to 4.4.2

then I upgraded php version to 4.4.2

and now I didn't change anything related to indexu files or mysql
But it seems that there're some changes on my western characters, they changed to ??? characters which I didn't know why they are.

In addition, there's no problem in my mysql database about the western characters, they're correct in my database but problem is on my site

The problem is on the category names.
Also when I click these categories(which has this problem), it gives "page not found".

I need help about this issue.

Regards