Adobe Digital Editions Won't Open

I've been using Adobe Digital Editions for years now and quite recently, it hasn't been able to open. This is the only thing I see aka a transparent box.  If you look at the picture carefully enough, you'll know what I'm talking about. 

I suspect that maybe my library has too many books (3000+) so that's why? But it could be another reason.  

I have a macbook pro and at first, I think I needed a software update but turns out it's unrelated. The problem is still not fixed and I'm pretty desperate in wanting my library to open up again. 

I have a lot of bookmarks and I don't remember the books I've read. I don't want to start all over. I just want the software to open again so I can delete some books. There's also no support for this software so I can only turn to this forum. 

Any ideas on how to fix this?