When you download a document it is saved locally on your computer in a folder called "Temp". This is where your work is saved until you save the chapter back to the server.
If you need to retrieve a document from your "Temp" folder, because of a system or application crash, you can do so in a number of ways. (The easiest way to access a recent file is to open InCopy/InDesign and select "Open recent" from the "File" menu.)
IMPORTANT: To make sure you open the correct file please use the guide found on the CtrlPrint server on the page where you downloaded the chapter you need to locate. (This is the page that appears if you click on a chapter name in the menu on the left side of the screen. It should show a red padlock and indicate the chapter is locked by you.)
For information about how to locate your "Temp" folder please see the section found here: Locating Your "Temp" Folder