@kimmy You know, actually maybe, I never tried this but maybe using a software like “recuva” only in the Pencil2D folder in the temporary files section can help recover the deleted files. Here’s a list on file recovery software.
It could be theoretically possible to recover the uncompressed folder with most PNGs that once existed in a previous working version. Again I’ve never tried this so I don’t know how that would work, but if nothing else works, this is the last option I can think of 
EDIT: I found this older video tutorial using recuva. It should help. It is SUPER IMPORTANT that you don’t install or create anything else that is “new” so the hard drive sectors that still might contain the deleted files are not overwritten.