We've all been there - you're going along beautifully, creating the best written thing known to mankind when your computer crashes, the program falters, and you have that moment (or hours or days) of panic because even though everyone tells you to back up your manuscript it's been (a week? a month?) since you have.
This anguish (followed by the purgation of reformatting your computer) are the layers of Hell that Dante forgot to write about (that is, writer's hell).
You probably hear it often but I'll tell you once more. Don't be a fool. Back your work up. Create a system and stick to it.
If you're like me and you replace your computer every few years, you'll be thankful for this. Of if you're like me and you have a habit of buying cheap computers because the promise of a mail-in rebate is enticing (darn you marketing ploys you know me so well!) then you might find that when it breaks you're unable to retrieve your files. I lost tons of my music and ebooks that weren't saved elsewhere- not to fret - most of it was public domain and easy to find online but some of it was indie and is no longer available on the internet. Learn from my mistakes. Invest in an external drive or use your cloud. Do what you have to do just make sure you save your projects in more than one place.
The moral of the story is- if it is digital and you don't want to lose it, back it up or there will be Hell to pay.