Thanks to SkyDrive Version History

Should you be stupid/unlucky enough to overwrite a file you have stored on SkyDrive you might like to know that you can bring back previous versions of your files by opening Version History. Open your folder in the browser via https://skydrive.live.com/ and right click the file name.

Select Version History from the menu that appears and then travel back in time to get the file that you want.  This saved my bacon tonight.