Powerpoint wiped when moving its location (while it was still open)

Hi there.

How can I find a PowerPoint I have not saved recently?

I have been working on a PowerPoint for the last two weeks. I regularly save it. I had it open and moved its location to a new folder.

After doing this, PowerPoint said I could not save this. I tried the 'Save As' option but it would not let me save it.

When I went to the moved PowerPoint, it was all blank. So I've lost all my lesson planning (I'm a teacher).

Is there some way to get this back as I've been working on this for a while now?

I am running a Macbook Pro Retina which is about 5 years old.

The PowerPoint I am using is Version 16.16.25 (200810). 2018 Microsoft for Mac.

Thanks (Have I posted this in the correct section?)