@Chris1 Hi. Sorry to hear about your current issue. Unfortunately there are only a few ways you can try to recover work, but they all assume that your file was either corrupted (but it still has drawings inside) or that you have an existing backup file with enough drawings to only redo it partially.
We’ve had reports of similar issues to yours happening when an antivirus or a similar software erases the operating system temporary file folder where Pencil2D stores your working files during any given session.
The problem is that if your drawings are erased without your consent and you end up saving the file, Pencil2d will simply store the blank keyframes without knowing that there were any images there, since it thinks you never had anything in the first place.
It’s certainly a bit frustrating but it’s not something we or the software itself can control. In this case you have to make sure to backup your file and save additional copies of the project to go back if something goes wrong.
The last chance I can think of getting any drawing back is to go to point 7 on the following guide Pencil2D Project File Corruption Prevention / Partial Recovery Guide and try to use CCleaner’s Recuva file recovery utility to get any file at all.
Note that this is advanced software and if you don’t handle it with care it might damage your computer. Consider asking someone knowledgeable about computers to test it out for you if you want to attempt recovery.
Other than that I’m afraid you might need to start from an earlier version of your file.