locating lost progress on the session I've been working on

Ive been working on a session and saving all through out the session as well as when I'm finished. every time i reopen the session it started where i left off. randomly one time when opening it opened me up to where i was a week ago and i lost a weeks worth of recording and progress. I looked up back up dates and none were listed as if I hadn't saved any of my progress through out the week. please help 😟