Recently a writing friend lost some of her work - because she accidentally threw away the memory stick it was saved on and hadn't backed it up elsewhere. It contained research notes for a book she's working on and which has a tight deadline.
Another friend replied to this news not just with sympathy but the revelation she'd once lost all of her short stories, again because she'd not made back ups.
Please make back ups of all your work. Computers can crash, memory devices can become corrupted or lost, equipment can be stolen ...
There are lots of ways to back up your work. You could use memory sticks, cloud storage or make printed copies. If you have a website you could upload it (and keep it hidden). Emailing files to yourself is also a possibility.
Personally I use hard drives, as shown in the photo. The two small ones are mine and each holds everything I've ever written (I've written a lot!) and has space for much more. One usually lives in the camper van, and the other on my desk.
If you've ever lost work, or would have done had you not made a back up, please share the experience to help others avoid learning the hard way.