@Loop Hi. This is unfortunately something that is out of our control as it is well known that interrupting the save operation will inevitably corrupt a Pencil2D file.
To deal with that for the moment we’ve created the following Pencil2D Project File Corruption Prevention / Partial Recovery Guide
Please try to follow that guide to recover most of your work, but bear in mind that it’s possible that still some of it has been lost depending on how much time passed from starting to save until the blackout and you won’t be able to recover the main file that lines up the drawings, so you’d have to line them up again.
Recently as well I also recommended someone another potential method if the guide fails, which might recover a previous set of existing files from your temp folder (if you read the guide you’ll understand), but it is an advanced solution that needs to be done step by step and with utmost care. Follow the link below to try that as well at your own risk. Ideally what you want is to recover the XML and PNG files as much as possible to avoid re positioning the drawings and in case you lost drawings well, to get them back.