I created a solidworks parts file in 2015 x64Edition SP5.0 and have been working on it for the past month.  Recently when opening an assembly that contained the part, I got an error message saying:  "An error was encountered while trying to open your file.  Contact Technical Support for a possible solution".  The file is grayed out in the assembly tree and when I mouse over the file, it shows the message "The file for this component was saved in a future version" .  How does this even happen and how do I get me previous version back?  Right clicking on the file in my windows folder and selecting the "Restore previous versions" did not help as there was no previous versions to restore to.  Any suggestions?