error: You must be logged in to access this page, go to logon page
 

All has been fine with my emails but today morning when i tried to log on I got an error message "You must be logged in to access this page, go to logon page" I dont understand why even when i supply my correct user name and password, please help

No real information to help you. And it does not seem to be related to Linux. Ask a moderator to move to general.
You should be giving us more information. What site? What application? What distribution? How? etc. etc. instead of assuming that we can read your mind.

It could be a problem with your webmail service, whatever that is, OR, it could be a problem with your browser (cookies, javascript, or just a buggy browser or plugin interfering). If you are trying to open a bookmark or a link discard it and use your hands to enter the root url to your webmail service in the form of www.whatever.com in your url bar. Then login if necessary and try again.