September 4th 90% drop, robots file

At the update of August 20th My blog peaked to an all time high, but the September 4th update completely destroyed it, most of the traffic was from google search engine and now it's down by 90%.
In addition, now at the webmaster tools, I see this:

This does not look good.
Any ideas? I know many people got hit by this update.

See original post by RON6