Hi 
I’ve opened my old works in progress today. Scrivener told me it would do something with the file format. And now all my chapters are the last chapter of the book. I am freaking out!
Has this happened to anyone, and is there a way to get the words back??
Hello, and welcome to the forums. I can’t diagnose what’s happened to your writing, and I’m sure that others with greater knowledge will reply soon - but to retrieve your writing, have you checked your back-ups? One of Scrivener’s strengths is that it makes regular back-ups as a matter of course; the details of when and where are to be found in the Back-ups pane of the Preferences menu item. Before you open your back-ups, it may be worth downloading and launching the previous version of Scrivener (i.e. the one you were using before Scrivener told you it was doing something to your files) from this website, so that you can open your writing with the version with which you created it.
I’ve experienced similar when all my chapters became chapter number one, i.e. all documents within the Binder suddenly contained the same text and all else was lost. I have no idea how and why this happened, and I didn’t report it to the developers. It didn’t happen immediately after upgrading. This was resolved simply by reverting to an earlier version of the project, an hourly Time Machine copy in my case, but I’m sure the Scrivener backups work as well.
If you could send a copy of the project to technical support it would help us figure out what went wrong, and potentially how to fix the problem so that others do not encounter it.