As you will find when you continue to research, the results will be variable. The process is supposed to automatically take a backup of your device before starting and restore from that backup when the process succeeds. But, this is, as I say, how it is "supposed" to work. There is no substitute for good manual backup processes to protect your critical user data. You can find full instructions for backups via the link in my auto-sig on this post.
Occam's Razor nearly always applies when troubleshooting technology issues!
If anyone has been helpful to you, please show your appreciation by clicking the button inside of their post. Please click here and read, along with the threads to which it links, for helpful information to guide you as you proceed. I always recommend that you treat your BlackBerry like any other computing device, including using a regular backup schedule...click here for an article with instructions.