After upgrading to Yosemite, I noticed that some of my iCloud files were missing. Id done a clean install, set my machine up as a new Mac and used Migration Assistant to transfer my data. I didnt transfer everything, just the applications and documents I wanted. I knew I hadnt deleted the files and my other iCloud files were there. Fortunately, I found out that iWork files stored in iCloud are automatically kept in the ~/Library/Mobile Documents of your Mac and you can retrieve them from your Time Machine backup. By default, the library folder is hidden and you have to use the following instructions to find it - http://ianlunn.co.uk/articles/quickly-showhide-hidden-files-mac-os-x-mavericks/ By navigating through the last backup, rather than using the Time Machine application, I was able to recover the folders for Numbers and Pages. Comparing the folders, I found that, for Numbers, my iCloud account had 18 files and yet the recovered folder had 21 files and, for Pages, the iCloud backup had 11 files and the recovered folder had 14 files. I dont understand why some of the files were missing. I would say that I didnt transfer all of my data using Migration Assistant. There was around 192Mb of Other data which I decided not to transfer. I assumed that as my Numbers and Pages files were stored in iCloud they would not be affected by the transfer. So, if youve just upgraded, I would suggest you check that all of your iCloud files are still there. Once the Time Machine backup has been overwritten, there would be no way to recover this information.