I have been working on a real estate site from past 3 months. The links have increased gradually from 19 to 3450. There were 3450 links on friday i.e., on 8 Feb 2013 as well. But(11 feb 2013) today I found 19 links in webmaster tools for my website. Could any one please explain me the reason behind the decrease of links in Google webmaster tools with in 2 days of time. What could be done to get back the original links.