"WAH! I copied the .COBOL back to .COB and started over again. As I knew what I wanted to do this time, it only took about a day to re-do what I had deleted."
When this has happened to me, I end up with better code than I had before. Re-doing the work gives you a better perspective. Even if functionally no different it will be cleaner, well commented, and laid out more consistently. I sometimes now do it deliberately (although just saving the first new version, not deleting it) to clean up the code.