Why can't I login into my Imessage?

I am unable to login to my imessage. It keeps saying my appleid or password is wrong but I am sure that I typed in the right id and password since I was able to log into my account on the Internet/Chrome. I didn't even get to type my password since it says it was wrong when I typed in my appleid. Before, I've also had other issues. For example, when I first tried to login to my imessage a few weeks ago, I kept getting errors about how there was an error during authentication. Later, when I was finally able to login to my immessage and was able to use it for a few weeks, I was suddenly unable to chat or read messages even though my Internet was fine and so, I tried logging out and into the account which leads me to my current problem.