If there is an autosaved version, then when you edit, an alert message appears just under the card header (like requests about memorizing passwords in your web browser), letting you know there is an autosaved version, with a link to it (in the Changes tab).
Also see add setting to default to editing autosaved.
this is a duplicate of have a link to Autosaved Draft in Edit mode
--Ethan McCutchen.....2013-03-21 15:59:31 +0000