How can I get Authenticator to work on my phone?

I had a serious problem with the app Authenticator on my newly bought phone today. At some point, the screen got locked and I couldn't unlock it. I entered the last password, the password I use for my Microsoft Account. It just wouldn't work. Currently, all my accounts are working. I have extracted a security code for my Microsoft Account. I want to make sure that my accounts are protected. And I have nothing to hide. I tried many things today, trying to contact support. It didn't go through. So this is me asking for someone who is knowledgeable if they have an idea how I can get the Authenticator app to work. Thanks for your time. Best regards, Serge Lauper