Importing Music Library.xml

My computer has shut down while iTunes was playing, and since then I am not able anymore to open my iTunes Library.

My iTunes Library is on an external hard drive (it is just too big to be on my computer). The folder seems to be okay on my hard drive, but why I try to open iTunes I have this message "Importing ITunes Music Library.xml." I tried to let it run for about 2 hours, and nothing happened. Should I just be more patient (since I have a lot of music on my external drive) or is there anything specific I should do?

I have tried to reopen my Itunes Library with the "option" key, but I still have the same message.

My computer is a macbook pro mid-2010. My OS is not the most recent one (El Capitan), but I think it is the one before this (Yosemite?). I don't know which version of iTunes I have, since I can't open it anymore (I would like to avoid creating a new library).