Thanks for reaching out. When you get this notification, it means that InDesign couldn't locate the document because it has been deleted, moved, or renamed. Or, the volume (server) on which the document is located may be currently unavailable. You may also check out help article https://helpx.adobe.com/indesign/kb/indesign-document-recovery.html for more information about InDesign recovery.
If the file is located on a server/network location, please try copying it to your local drive and then open it.