Problem opening Numbers document & Time Machine issue too

I have a Numbers doc which won't open - "Numbers couldn't read the file. You can try restoring to a previous version" - So I do that and the result is "No previous versions available. Error retrieving versions from Time Machine" - Looking at the folder with 2 Numbers docs that open just fine and the one which doesn't - the 2 docs show a spreadsheet type icon and the one which won't open shows the green Numbers icon. Other Numbers docs work just fine.

Any idea on what's going on???