System crashed but no autosave file found I had been working on a Blender file for about an hour when my whole system just crashed and powered itself off (using Ubuntu 13.10, and I had many applications open).

The /tmp directory where the autosave file is typically found had no blender files in it.

I just opened Blender again and confirmed that the autosave feature is working properly according to my settings (saving 2734.blend every 3 minutes).

So why is there no autosave file?  The /tmp directory had other files in it, so I don't think that Ubuntu crashing caused the file to be deleted.
It seems /tmp is cleared on startup in ubuntu by default, so
unfortunately if you had to reboot your machine everything in /tmp was erased.
The other files you saw in /tmp were probably created on startup.

Blender has some other backup systems (see this post), but if you did not make any manual saves I'm afraid there is nothing to be done.

Autosaving to the hard drive:

You could change the directory blender uses to store temporary backups to a location on your hard drive by changing the Temp location in CtrlAltU> User preferences > File:



Note that this setting controls the location of everything blender puts in /tmp by default, not just the autosave files.