aakk9999 - 3:31 am on Jun 27, 2013 (gmt 0)
Back in May, another of my sites was doing really well. Then I made a minor little change to the lay out, and from that day forward, EVERYTHING COLLAPSED.
It still hasn't recovered, no matter what I did to get it back to how it was!
Have you tried to match the date the site collapsed with any of known Google updates happening in May? It is possible that the site would have dropped without any of your layout changes, i.e. that the drop is result of Google algo change and not because of your layout change.
Especially as you have reverted it to how it was and did not recover. From my experience, if changes are reverted, in most cases the site recovers after a short while - unless you keep tinkering with it.