The error message might be related to damaged field codes or possibly another issue. Suggest you bypass the forum and contact tech support which may be able to restore your document if it is indeed damaged. Looks like tech support’s “chat” feature is live now so suggest you either chat, call, or email:
Technical support http://endnote.com/support
For help using EndNote
Monday – Friday, 9 a.m. – 8 p.m. Eastern (GMT -5)
+1-800-336-4474, press 4