Sorry to hear about the trouble. Please try the third step shared here: https://helpx.adobe.com/xd/kb/issue-saving-xd-file-creative-cloud.html to restore the file. If that doesn't help, will it be possible for you to share the file with us over a private message? We'll check that on our end and will share the next course of action. Please add the file to a shared location like DropBox and you can share the link in the DM.
Note: While sending the DM, please add this discussion link in the subject.