Have you ever experienced typing a long document on a word processor then all of a sudden your pc shutdown or reboot when you are almost done? Then you realized that you haven’t saved the document yet? How did you feel? How about an HDD containing important files and souvenir photos suddenly crashed without any backup? I’m sure that you will feel the loss for several days especially if there is no way to retrieve the files. I’m just giving you a hint how important to save frequently and to secure a backup of important files.
For the word processor, I’m sure that your system can recover part of what you typed. For the data loss, there are available tools but I’m not sure how much files can be recovered. The key is to do a regular backup of your files to avoid this kind of loss. It is good to invest on a spare HDD or good-quality optical disks for backup. Anyway, the prices of HDDs are much reasonable nowadays than before. There are also free data backup services available online if you really have a tight budget. But of course, free services most of the time are also limited in capacity.