Hi,
In order to help you further with this issue we need to validate the following information:
1. What is the Operating System you use?
2. What is the version of MSN Software?
3. Where there any changes made on your computer?
4. Provide your impacted email address?
Things to try:
Firstly change the password on your email account and update your personal information on http://www.login.live.com/
How to find the version of MSN Please check the link below
http://answers.msn.com/solution.aspx?solutionid=b1568530-1f0b-4040-99ab-f9cc6c60d532
Thanks!