Try right-clicking on the folder(s) in windows and "Restore previous versions"
>>Why does this happen?
Well historically it has been the IOC parser detects some syntax error or anomaly, perhaps due to bug fixes (old file now has unacceptable syntax), and rather than recover gracefully it fails hard. As I recall sometimes this had a poorly worded or ambiguous popup giving you a 50/50 chance, or worse, of destroying the project. ie About to erase current project, would you like fries with that? Yes/No
In more conservative auto-gen tools, you'd archive prior content rather than unlink or create-new over the current live project files. At the very least backup any files with user generated content. In a well considered implementation, you'd provide a means to diff/merge, or recover things from the journal of changed project files, and pin/peripherals settings.
How this stuff gets written and tested troubles me.
