pikadroo:
Yeah, all my final source gone. Redoing it all today, very devastated and I had it perfect. Thank you all for the sympathies, it's good to know I am not alone in this. 
Any sympathy I might have had evaporated when you blamed the Arduino IDE for your negligence.
Finished it, it was working perfectly and in 8 hours I never once realized that I had not hit Apple + S. Which is really strange for me and not to dwell too much on my age but I come from a time when you had to do this every 10 seconds on 10 different floppies because a single change in the environment could cause a chip to glitch in the computer which would mean disaster. Had to program with oven mittens in those days.
I wrote code for pay from 1980 on. I'd work with one backup floppy and keep 2 or 3 disks in a folder that I updated once a day.
Perhaps it was the Verbatim 5 1/4's, still had good data ten years later when we found some and scrounged up an old FD.
Or maybe my results came about by avoiding overpriced egoware from Apple.
Anyhow, I think the point here is. Arduino, listen up I am talking to you. Keep my $600.00 and put that money to fixing this problem. The problem being that, while I can appreciate that there isn't an auto save over my last saved version, there should be a plain text file being saved in the Arduino directory that is current. This is common practice with editors these days that they can recover a document after a crash. In fact, and quite ironically, as I type this I notice the web site is saving a draft as I go. So, let's get on that eh? 
Drew
What is a problem for you who maybe should learn about the tools you use is something the REST OF US can only scratch our heads at the the silliness of it. Your source gets saved to the project folder in your Sketchbook folder, or at least MINE does.
The IDE is not terrific. There are many threads archived here about alternate IDE's including Microchips that you have to run Winblows to use so I can't tell ya bout that. Code::Blocks has a special Arduino version, or did. Geany and Eclipse work.
Well for sure, common practice is ignore the manual. It's the uncommon ones who RTFM.
Here's a tip for Arduino. Give your project a meaningful name and add a 4 digit version number to the name.
Whenever you go to add a new section, first Save_As the name with the next rev number and your old code stays in name+ver folder while your new work is in the new Saved As folder.