Mail using iCloud imap failed

My mail has suddenly locked me out, I continue to receive as usual on my iphone but I keep getting asked for the password on my mac air. There is no reason why it suddenly stopped, nothing was changed! Now I have tried all my password combinations to no avail and am seeking a solution to get it working again. Can anyone help to clear whatever was the password and et access to the mails that I can see on my phone?

I have a mac air rinning 10.8.3

the account is showing icloud imap

incoming server imap.mail.me.com

outgoing smtp.mail..me.com

I keep getting message e:mail can't connect to the account icloud"

Thanks