I recently experienced a major technical breakdown on my primary PC device - a Toshiba Laptop Windows 8.1. To make a long story short, while troubleshooting a client's system, several changes were made to my system configuration in the intent to gain access to the client's wireless system. The following day ... I lost all wireless capability, I could only boot to Safe Mode, I could not access or use Windows Recovery features, etc.
By chance, the day before, I had created system backup of all Library files and also created a System Image saved to an external Drive using EaseUS ToDo Backup. I 'frantically' went to restore the image I had saved the day before and within 45 minutes all files, programs, and settings were restored to the date of the System Image created the day before. I was saved. Lesson: do not intellectually know you should backup your PC routinely - DO IT!