Hi Pascal. Thanks for your reply. Somehow I fixed by myself and now it's working perfectly.
Well actually I don't have a lot of knowledge about the web design, I'm just using for my own shop.
So I was looking for something else to change but couldn't find it so I was trying to change a lot of things last night and also changed "Generator" from Back office and I think the ".htaccess" file had been changed.
Today I just tried the same things from last night again and when I changed the "generator", it showed me the diffrence but not all the pages. Then I rewrote the "friendly url" again, then all pages went perfect.
From now on, I have to careful to change, especially the part which I don't know how work.
Thanks.
Hiroko