Help - Updated Image- Old text

[archwriter]

We have a file that we have been working on for a week.
each day we save, and set the autosave, and all was well, updated text
and images
this morning, we added one more slide, then discovered that all the
images are current, but the presentation reverted back to the text from
4 days ago?

Q: how/ why did this happen?
Q: can we retrieve the newer text?

thanks