There is no 'autosave' in Word, only the saving of recovery files, and it appears that worked as intended as you got the recovered file. The recovery file is saved at the specified interval in the folder indicated at Word > Options > Advanced > File Locations > Autorecover files.
If the user worked for 'a day' without once saving the work, that user needs to rethink her working practices and save more often. CTRL+S every time she stops to think will do the job and minimise the possibility of work loss. See also
http://www.gmayor.com/automatically_backup.htm