In my website if index page is having a good PR say 6 and there is an internal page that is linked with the index page using the nofollow attribute and I putted it in robots.txt to disallow its crawling. So is there any possibility of getting PR for that page using any technique like link building for that page etc.
robots.txt will only stop it getting crawled. If someone else links to the page with a dofollow then i can see no reason why the page could still get google PageRank as it would have links pointing to it then.