DON'T PANIC!

I recently experienced the trauma of learning that my computer had picked up a rather nasty virus, and had to take it in for virus removal.  I think I can safely say that almost all of us writers live out of our computers these days, so when things like this happen, there is a certain panic that takes over the brain.  I was concerned about my stories and what might happen if they were to be lost.  (thankfully, all of my files are intact and backed up, just in case)  Let this be a lesson to you all, make sure you back up your writing files every now and again.  I'd recommend once a month or so, although depending on volume, you may want to do it more often.
Situations like this remind me of how important writing is to me, and tend to motivate me to produce more work.  Years ago, I had a similar situation when a power surge caused my computer to crash.  I lost almost all of my writing, but in a way, it was to my benefit.  As I said, this was years ago, so most of the work I had at the time wasn't very good.  This left me with a handful of old drafts and whatever ideas were strong enough to stick in my head.  I think this loss of old work payed off in the long run, because it freed me up to write new things, and improve on old ideas.
While the loss of stories is something that none of us want to experience, I find that sometimes it can help one's growth as a writer.  If you have a story that just refuses to be finished, and frustrates you to no end, you might want to consider just deleting it.  I know that it might sound radical, but sometimes, it's for the best.  If the idea is good enough, it will stay with you, and you'll figure out a better way of doing it.