Hello Martin

I moved your post to the Xara Graphics Chat where it should get more attention.

Can you create a new document without any problems? If so, you can always recreate the document (easier done than said, granted).

But before you do that try opening one of the recent backup files and see if this helps (File > Open Recent > Backups...)

The backups are dated and so start with the most recent. If you can get one of these to work you will only have to redo the most recent additions.

And if you do get one to open OK, then be sure to save it with a new name before you do any work.