After 1 thousands backlink within two months my site vanished from google 1st page top 3 to 3rd page top 5. It's PR is same pr-5. I had 60(2 months) days and 20 backlinks per day I made. I think this is not about backlink because 20 backlinks each day is natural for pr-5 sites. So what will be the possible reason for that?
Today's trend is diversity in every aspect. Aim for quality links rather than quantity. It's a slow and painful process but the effects are long-term.
Just focus on keywords, and make really quality links like get links from PR pages like 2-3-4, if you get single link from here that will be as same value as you make a 20 links with no PR .. thanks regards
May be your site has been penalized by Penguin. Try to find out bad links and remove them. And apply quality natural link building process.