Yesterday 4th Nov someone hijacked my e-mail account and sent e-mails to my contact list and other addresses listed on my received e-mails.

I have checked my computer for viruses and updates and changed my password. No bogus activity today.

However it seems that three months of inbox e-mails have been deleted and the last three weeks of sent box also deleted.

Is there any way to retrieve these e-mails, and can anyone tell me whether the information contained in those e-mails might have been read by the hacker?

Hi verythick,
 
Due to security reasons, we can’t confirm if someone else hacked your account or was able to read your e-mails.  Post your-mail address here so we can try to retrieve your lost e-mails. 
 
For your concern on the spam messages that were sent from your account, you can read this solution article:
 
http://windowslivehelp.com/solutions/safety/archive/2009/04/29/recent-reports-of-account-hijacks.aspx
 
FYI: I’ve moved your post to the proper forum, Lost or Deleted Emails.