not sure what the hell has happened, i havent done anything to my site to cause these changes can anyone explain why such a huge drop in links?
This happens, i know how you feel. Its the crawlers re crawling the sites. I keep posting, I once lost 100 backlinks in one day. I'am now at over 2,300 in 3 weeks
Your links will decrease as all those links are buried or deleted away from Google and then your backlink will decrease ridiculously.
Maybe, some of your baclinks before have already remove your link (this usually happened in link exchange partners) or the pages where your previously linked was already de-indexed by search engines that is why it was not count as backlinks anymore.
Google doesnt display all the backlinks it knows about, checking with yahoo site explorer is more useful.
Where you are checking your back links? try to check them in yahoo site explorer. Still if you get same results than may be for short term also. Wait for a while may be you get them back.
The thing about link building is you will get links dropped, added and such its apart of the game... you just need to build backlinks weekly/daily.
Maybe the page that give you backling deleted, or maybe not indexed anymore by google. Do lot of SEO so you can get more backlink again
I have noticed some reason why your google backlink might be decrease 1. Either your link has been deleted from that site from where you are getting link 2. Either google does not value that site from where you are getting link due to spam. But why you are so trouble by backlink, your backlink decrease does not mean that your ranking will also down, if you again build quality link then next time when google update backlinks then your backlink will surely increase.
It's most probably that if you log into your webmasters tool you will see all the links still intact. Google likes to consolidate and only display a few backlinks when you try link:www.yoursite.com So, log into google.com/webmasters and see if you still have your backlinks there or if you really lost some from the sources you received them!
Maybe some sites removed your link so try to check or some pages that your link used to be is no longer there.