Only home page url shown up for all keywords in SERP?

Hi all,
This is the website knowledgeadventure . com . Actually this website is about educational games for Kids. Till few months ago no SEO was done. But according to its age(11+ yrs) and trustable(linkers) there was PR5 for all the pages(?) and also it was showing some average positions in the SERP. And after few months of normal link building strategies like bookmarking etc, for many keywords it started to show in the first poistion and in between 5th position. There were lots of traffic for targeted keywords. But suddenly now everything gone only homepage url is showing in SERP result for all the keywords searched. No inner pages url’s are showing.

For eg for keyword “toddler games” in SERP it use to come at 1st position but now its showing in 17th positions and also it shows the url of only the home page not the toddler games inner page? Why is it so? Any bigdaddy effect? How come Google excluded all the inner pages from its SERP

Which search engine are you targeting? If its they have just rolled out the panda/farmer update (24th Feb) - Lessons Learned at SMX West: Google’s Farmer/Panda Update, White Hat Cloaking, And Link Building

I’m targeting for Big G Google only. So what are the effect about it?

Besides bookmarking, what strategies did you use for link building? wait a few days to see if your position will come back.

I had created squidoo pages, hubpages inter linking with each other and then did few blog commenting. Thats all not more than that. For the bookmarking itself the keywords started to rank for nice positions. but suddenly now no page is showing in the google when searched. Only home page is there for all the search.