Can not log into iTunes on MacBook Pro, using correct name/password

Frustrated - I went to iTunes this morning and my library was not there. I ended up logging out and then back in. It took my user name and password but nothing changes, my library never shows. I just get the defalt screen showing me what music is. This is only happening on my MacBook. I still have full access and everything is working on my iPhone and iPad. It acts like it is not seeing my login. I have shut down iTunes and restarted the MacBook multiple times trying to fix it but nothing makes any difference.