I swapped out internal HDDs to burn something and when I put them back in, all my edits are gone! I had done some file restructuring in FCP such as making a new folder in the FCP browser, and that new change is still there, but all the edits are gone. The clips show 'Not Set' for both in and out, as if I'd never touched them, and none of the restore points show that I did any editing at all.

There are no warnings that anything is wrong. Just nothing there. What are the edit files that I should be looking for, as the sequence is there, yet just showing 00:00:00:00.

I think the problem was in copying the file into a folder within the browser. But it worked when I had it open. Where can I look at this point?

That sounds like a bit of a wonky set-up. Have you tried opening up some autosaves from the Autosave Vault in Final Cut Pro Documents?

Yeah, there are about 80 of them, saved every ten minutes. Each one shows 00:00:00:00 for the only sequence. There's just nothing there. I'm wondering if a sequence has its own file(?)

Chances are you had cache or other meta-data that was being saved to the HDD you swapped out which is why your sequence info went missing.

Try using a "reconnect media" command in your project and see if FCP can help you find your missing sequence/s. If that doesn't work then you'll have no choice but to rebuild what you lost.

It's never a good idea to make any core-level hardware changes in the middle of a project, especially if your media-managment scenario isn't bullet-proof to prevent this type of thing happening.

I'm thinking you're right. I didn't think it would be a big deal to swap the drives since the file was closed while the other drive was in. I've now started from scratch with a new file, so as not to risk it. That's a lot of work wasted.