[SOLVED] My theme just went completely weird and lost all the formatting ive done to

Hi all,

Ok. I was just working on my theme and changing a few things around, nothing major, just come colours and fonts and when I refreshed the page it went completely weird on me,.....lost ALL the formatting I have spent the past 2 weeks on and everything went out of sync and all over the page, the picture changed, the pages and sidebar changed.....its all gone mad?

What can I do to get it back and WHAT has just happened to it???