Hello,
we are sorry, but the changes cannot be recovered. The "Edit PDF" tool keeps all changes only in the open window until you save, it does not write a temporary copy. After the laptop switched off, the edits were lost.
For longer work please save in between, for example as a copy of the PDF. This applies to the online editor as well: https://tools.pdf24.org/en/edit-pdf
The PDF24 Reader can restore unsaved changes after a crash since version 11.31.0. The next time you start it, it asks "Restore documents?". For "Edit PDF" this does not exist yet. We will add it to our list.