The patient may have some good days interspersed with the bad; the memory may be somewhat sharper even at certain times of the day.
However, there may come a time when certain memories are lost forever.

I have read and even seen videos that music that was once familiar to a patient, and to which he/she may sing along, can , in effect, kick-start the memory for a brief period. Perhaps that would work with seeing known objects or places.

The return of memory would be temporary.