An old bug is back in 2019 SP02: Rendering an animation with "create movie"-option checked on, deletes all files in
the image output folder!!!! Files inside folder and folder are not affected. To avoid deleting uncheck the "create movie"-option.
I lost 10 finished renderings because of this bug!!!
have u checked your recycle bin, if the deleted files are there? worst case scenario try file recovery software to try and rescue those lost files.