I would suggest contacting Technical Support.
Technical support
For help using EndNote
Monday – Friday, 9 a.m. – 8 p.m. Eastern (GMT -5)
+1-800-336-4474, press 4
or via the web
http://ip-science.thomsonreuters.com/techsupport/
If you had been using Time Machine on your MAC you might be able to restore the library with that utility.