yesterday my site was showing on page 13 of google.co.uk but today it showing on page 37, even though i am building more links etc.. i dont understand some time what is usually happen and website certainly disappear from google, some body can explain to me. thanks
"site was showing on page 13" is no way related to Page ranking... give here complete detail like for which keyword it was on 13 and your URL..."
Please give the other details also so I can help you. You are saying that your site is on that number but for which keyword it is..
yes sometime it happens, dont be worry just do more organic SEO and get strong backlinks, maybe you have submitted ur website to a bad web directory or simmiler practise with your link, therefor you are experiencing this problem.
it took me 2 months to show my site somewhere and suddenly it just disappear, thats why i am disappointed.