Docker project: cleaned up and rebuilt—image deleted. How can I recover the data?

Unfortunately, I’m pretty sure I know the answer, but just in case there’s a solution:

I had some HTML pages created within my Docker container (via Container Manager) that wouldn't show up. I ran `find / -name "myfilename" 2>/dev/null` in the container's bash terminal and found them, but they were in the wrong folder.

I tried moving them to the right folder using a bash command (a mistake—always do this manually);

they became invisible again, though the command could still locate them in the correct folder (I could see the folder and they were apparently inside, but I couldn't actually see the files).

I copied that folder elsewhere as-is, but it still appears empty.

Then I made another mistake: I rebuilt the project (cleaned and recreated it using the base folder—no visible items were deleted),

but the invisible HTML files are now gone completely, even when using the command that had previously found them on the NAS.

From what I've researched, this might be due to a folder not being mounted correctly; the files were likely saved in volatile memory, so rebuilding the project wiped them out. If anyone has any ideas, I’d be very grateful.

Thanks!