Hi Raj, I’m sorry to hear that this issue affected your account. Make sure that you've also changed your secret question and answer and alternate e-mail address as suggested. You can also check on the link below to get in touch with PC Safety line for additional assistance when it comes to protecting your computer:
http://www.microsoft.com/protect/default.mspx
As what was mentioned, one of the causes of this is malware. This is the reason for the messages that were generated from your account and your deleted ones.
If you want to keep a back-up of your messages, you can opt to use the Windows Live Mail e-mail client program. This program lets you download your messages into your local computer’s folder so you have access to them straight from your hard drive. You can download the latest version at http://download.live.com/wlmail .
Note: To see if your computer meets the system requirements of Windows Live Mail, please visit the following link:
http://download.live.com/SystemRequirements.aspx