I gave myself a fright yesterday. Working away, everything going well, I attempted to cut and paste one paragraph into a different position - and succeeded, heaven knows how, in deleting the entire chapter. Granted it was only half done, and it's a mere 16,000 words gone into thin air, but those words had taken me a long time to get onto the page.
Needless to say, I quietly panicked. Instead of checking auto recovery, I wandered all over the place seeking the missing file, trying this, trying that and in doing so probably consigned the document to the outer reaches of cyber space.
I wailed out loud on Facebook and several kind people tried to help, but nothing I did brought the document back to my screen. It was a rude wake up call - I have got out of the very good habit of saving work to a back up every day, even twice or three times a day. Now I am saving it to back up every times I finish adding a few words to Chapter Thirteen - yes, it was Chapter Thirteen!
I have also re-set auto recovery to save every 3 minutes instead of every ten. Obviously my action happened between auto saves. so let my ill luck be a warning to others like me. Don't get complacent - save after every new piece of work!