i had 2 pr at my web page in first 50 days.but i changed ONLY dir. example domain.om/xxx domain.om/xyz and my pr is zero ? stylemo.net
PR stands for Page Rank and its relative to the URL. Changing the directory name means a change in URL. Therefor the drop. You can try a 301 redirect using htaccess file to preserve the PR and link juice to your new URL.