@mbru Sorry to hear you had this issue. While there are many possible problems that might be happening let me ask the following information:
- What is the version of Pencil2D you’re currently using?
- What is your current OS?
Note: To quickly answer 1 & 2 Go to the
Help Menu > About >Press theCopy to Clipboardbutton and immediately pressCTRL + Von your next reply so we can know this basic computer information. - Did Pencil2D crash at any point before losing your work? Like did it close itself without warning, or did it close with a warning?
- Have you been moving large amounts of frames before saving?
If you’re using Windows 10 this is likely one of the main causes for your work loss, so please read this guide before attempting to resume work [Guide] How to Train Your Pencil2D (Windows) Seriously don’t skip this as Win10 has been playing a big part on these work loss issues lately.
Apart from this, please upload your project here or online and send us a link. You can use wetransfer.com, google drive, dropbox, or you can drop the PCLX file directly on your reply box and upload it here so the developers can take a look at your file.
Other than this it’s hard to say what happened and it might not be possible to recover the lost work, however please make sure to read the following guide thoroughly to learn how to prevent these and many other rare issues that could happen as well as to develop a habit of saving multiple files to preserve your work. Pencil2D Project File Corruption Prevention / Partial Recovery Guide
There are some experimental file recovery steps at the bottom of the guide using third party software for Windows, if that’s your current OS you could try to follow to try to recover the lost frames, but this is a last resort and it’s done under your own risk.
I have to be frank, recovering lost data is very difficult if you don’t do it quickly and in the same computer where the data was “lost”, so after we try all of this you should prepare yourself to repaint whatever was lost, and make a point to keep a series of backup files to avoid these issues, not only with Pencil2D but with any software.
I’ve personally lost paid work with expensive commercial software that has 300x times more people working on than Pencil2D, and all I can say is that, software can fail, so we can’t always rely on it, as a future professional in whatever you will do, you always have to plan ahead for unforeseen problems & deal with their consequences. Don’t get discouraged, this is a part of digital animation & art in general that is unavoidable, but these experiences help us grow and next time, you know you won’t get caught in a bad spot 
