buddy the PR is assigned by Google after counting your websites backlinks and then verifying the quality. the Google compares your competitors backlinks also hence based on the comparison New PR is assigned after every cached report. Hence PR is a fluctuating matter. Dont worry do more SEO , increase your backlinks. your PR will again increase. Cheers!
the page rank provide by the google algorithem.the google arrange the popularity of site and his tag and keywords.
Most likely Google have adjusted their algo and your site was affected. Best way to offset this is to continue building backlinks for your site.
No alternative other than one way link exchange......... 1. Write some quality article and do submit the same to different article directories such as Ezinearticles.com, and so.......There are lots of free article directories on WWW. 2. Do press release if your firm is come up with new things, and so....Highly Appreciated 3. Do Social Bookmaking and try to spread the same all around Thee are lots of more ways to get quality backlinks........Try to get updated with the current SEO need.................