Have you tried the short cut for Undo?
If you have not yet closed the file, try exporting to .idml.
Yes, I did but it doesn't work..
@ Peter Spier:
If I do so, can I undo it then?
The problem is that I really have to be able to undo it, because otherwise there will just be 23 empty sheets.
I will try it though, thanks!
Okay, I exported it to .idml., but as I expected, I was able to save it then, but I couldn't undo it..
So I guess my work is gone... I have to find a way how to undo the "delete layer" step.
If you success to export file to IDML, that means your file is backup and rescue from lost.
After export try to open IDML file again.
Sorry, I misunserstood that you had actually issues a command to delete the layers. At this point even autosave is by now also probably updated to the point where the layers were deleted.
See if you can open the file again, as a copy. Since it wasn't saving all this time, it may still have data in it. If it does, try a Save As or Export to .idml again, then close ID. Reboot and open ID again, open the newly saved file and make one change. See if you can save.
Thank you so much!
I'll try it out!
Well I was able to save it, but I was also able to do so,
when I exported it yesterday to idml. After exporting it i was able to save,
but that didn't help me, because I couldn't undo the fact, that I deleated the first layer. So my dossier is still gone. I don't think I can ever have it again, because now I did a reboot and the version with the blank sheets is just on the idml file and thats the version where the sheets are blank and an "undo" is impossible because it was saved AFTER the "delete layer" action..
I'm sorry, I probably sound confusing, I don't know how to explain it...
Are you saying you saved from the blank .idml over the original by using the same name, or that you somehow managed to save the original after doing the deletion, but before you discovered you could not undo?
If you did not save after the deletion and closed the file, the delteion should not have been saved and you should be able to open the file at the last saved state, but it sounds like you've saved it with no content.
I exported the original to idml after doing the deletion..
And then I could not undo it, because my undo-button didn't work for 2 days.
I guess I'll never get my work back, at least not the 3 hours after I exported it to PDF.
My design teacher understood it, because it was not my fault,
but it's still annoying, because I want to have my work back that I'm proud of..
No, you'll never get back any changes you made between the last save and the time the file was closed. If that was three hours work, that's unfortunate. My advice was simply a way for you to recover as much of your work as possible so you wouldn't need to start over from nothing.
Consider this as a good lesson in workflow habits. Save often, and I recommend doing a Save As with a new versioning name (I append a number) at each major change point where you are about to branchin a new direction. This gives you not only a set of backup files, but the ability to easily go back to a previous version and go in a new direction.
It's also good to develop the habit of hitting Cmd-Z (Ctrl-Z on Windows) for Undo immediately after you make a mistake, though it sounds like you actually tried to do this. File > Revert can be helpful too, if you've been saving right along.