Help restore or save passage?!?

Is there someway to restore or get back a passage?

Also does is the search prompt able to delete passages?

I had used the search prompt to find a certain passage. Then after working on that passage and others I notice that the passage was marked in yellow. I quickly realize it was because the search prompt still had the search words in it. So I marked the words in the prompt (at least I think I did), pressed delete on my computer and the yellow marked passaged dissapeared but not the words in the search prompt.

So either I somehow accidentally deleted a passage I wasn't even working on or you can delete stuff from the search prompt without any warning?

So I'm wondering what the hell happened and how do I save my work?