Excel file closed and now is glitched and possibly erased itself

First off, I am not sure how to explain this well, so stick with me. I had an Excel file and must have accidentally closed it because it suddenly was gone, even though it did not ask me if I wanted to save it. Anyway, I closed another Excel file I had open and it asked if I wanted to save the first one. OK, sure, whatever, I did. But now when I open that first file, Excel opens, but there's nothing there. I don't mean I see a blank sheet -- I mean I see Excel but there's just a giant gray space where the cells should be and all the tabs at the top are grayed out. See this screenshot: PsqkS4I.png (1914×1021)

Other Excel files work just fine -- it's only this one. Did it somehow erase my file? I have never had this happen before. Is there any way to repair it? I don't even know what I hit, but the document closed without asking if I wanted to save it, and then things got all screwy.