I described everything there already, with.. a lot of swearing while having a breakdown:
https://indigo.cafe/posts/617038

Please help, I didn't saved it before, it did autosave, and I restarted my pc to open the autosave data but it didn't helped too. I just have two layers left now the outlines and the color with the unfinished shading, did now for the screenshot a layer for a colored background to see the whole damage, and a layer for the watermark because I am paranoid someone could steal my art again