iTunes doesn't open and give a blank message I've been having troubles with iTunes : 
it was working yesterday morning, and after I restarted my computer it will no longer run, it just gives me an empty message box 



and if I leave it for a moment an error appears:



The problem occurred when I was on a old version of OSX, so I updated to Sierra and to the newest version of iTunes as well, didn't change a thing.
What I have tried :


restart computer
Install Sierra with iTunes 12.5.4
Try to remove iTunes, I just have a message : iTunes can't be modified or deleted since Mac OS requires it 
Try and download iTunes from the Apple website : the available one was 12.4.3, so when I try to install it tells me a newer version is already installed and stops.


Any ideas ?

Thanks in advance.
Exploratory troubleshooting: try holding the Option (or Alt) key down while you launch iTunes. Hold it until you see the following:



Now press "Create Library…" and see if you have any more success.

As a second option, try creating a new user on your system and see if iTunes works any different/better there.

These are steps to help you determine if the problem is the iTunes application or if it's something specific to your user account and its data.