recovering previous version of saved, protected document

[Carol]

I'm working in a protected document. I saved my changes
several times prior to inadvertently unprotecting it.
When I did that, I lost all the changes I made. I want to
recover the saved version of the document that I had just
prior to my mistake. Can anyone help me? Thanks!
Carol
P.S. The "version" category on the "file" menu does not
help. No previous versions are listed.