Mentioning the Amstrad CPC in another comment brought this back.<p>Sometime 1986-88. I am in my nurse training and I have to submit a multi-thousand word essay. I type away on my Amstrad CPC6128 which was running Brunword (a dominant wordprocessor at the time). Somehow I hit a keyboard shortcut which highlighted and deleted everything on screen. After staring to the screen for a few minutes I grabbed the manual, ran out of the flat to the local telephone box.<p>Called the developer - yes, his actual phone number was in the manual.<p>"Yes, the work will still be in the computer but it is impossible to get it back."<p>That was the moment I learned that backups are not optional.
Ages ago before mobile internet I had printout of a library I wrote, 10 pages in small fonts, to read/review on a long train ride. A couple of days later I accidentally deleted the file. No backup, no version control. I was able to type in all the code again thanks to the print-out. It will never happen again ... because I never print anything out again.