By default, backup files of your drawings are made at certain occasions, for example when you exit the program choosing not to save your changes. This makes it possible for you to recover lost files.
The auto-backup files are stored on the same location as you load your
drawing:
My Documents\CET Documents\autosave.
The easiest way to locate your back up files is to use the Open dialog box.
You activate/deactivate the auto-backup feature in the Control Panel which is accessed from the File menu. In the Control Panel dialog, select the Security tab.
In the Control Panel you can also change the number of auto-backup files per drawing.