I have created single page websites for some of my products. Now i am wondering if a website has only one page. would there be ranking problems.
It won't suffer any penalty, but it will be at a disadvantage. The more pages you have, the greater the number of keywords that you can optimise for, and the more content you'll have indexed by the serach engines.
The historical thought is that google ranks each page on a site separately. I don't believe this is true anymore and that google considers the value of a page on your site in light of the value of the entire site. Consider this, how many times did you google for something and it gave you a site with a single page. Off hand, I can't remember finding a single page site with google (& I sometimes jump down to the double digit pages to see what's down there). If your single pages have been around for awhile, keep the URLs (age has value). If it makes sense, what you'll probably want to do is create a site that combines them together. Then the old URLs can have permanent redirects to different landing pages that contain the old product. Of course, this is based on not seeing anything you have.
PR = Page Rank...not site rank I have a one page site that does fairly well...it is mine Wiggles Name Generator page.
Hey I saw your website. But remember as the pages of website is more you will rank better. and also your visitor will get good information. And still you able to rank well you are not going to get lead generation.
More quality content = More pages. SEO wise, I think it's not a good idea to have a one page website.