I check your suggestions befor!
for example look at this photo plz :) http://linkindark.persiangig.com/xoops.jpg

Is it cbb or an older newbb forum? The original newbb had date filters to be set by user. In default it displays only the postst from the last couple of months

newbb 3.08, how can i change filter date or turn off it?

One of the 3 dropdown menus down the posts can be set to show post from the last 100 days, from the last year, from the beginning and so on. I see those dropdown tabs on your second picture. The left menu shows 100 and I guess it tells you in your language to show the latest 100 posts

I'm not sure if you can disable this in admin, I don't have a similar forum by hand for checking...

thank u :) the problem is fixed with your guide.