Password request for e-mail on Me.com account

I changed to a me.com account and set it up in outlook mail on my PC. I've been using for several months receiving messages and sending them. Now it is asking for my password again to access the IMAP server and It won't take it. I'm not able to download any messages now. I can receive on my iphone & Ipad but not my computer without the password taking. I know what I put in is correct.