locked pages document says "The file format is invalid" after moving to new computer
I recently reset my mac air to factory settings, but before doing so, i saved a pages document to my USB. This document was password protected, and i still know what that password was. After i reset my computer and moved the document from the USB to my desktop, i tried to open it but got the error "The file format is invalid". This document is very important to me and i would be very appreciative of any help anyone can provide.
MacBook Air