When Microsoft moved my e-mail account from webtv.net to Outlook.com on 10/01/2013, all of my e-mails were in my Outlook.com account.  Most were in the  Inbox and some were in the Sent and Drafts folders as well as in various user-defined folders. 

Since then nearly ALL e-mails in the Inbox and many in the Sent and Photos folders have DISAPPEARED!  I've reviewed other entries in this forum and it seems I'm not alone with this problem.  Hopefully the following will help you identify the problem and solve this:

-  Inactivity is not an issue, as I've accessed the Outlook account several times since Oct. 1st.  Accessed webtv account almost every day prior to 10/01/13.
-  I access my account on-line, i.e. am not using a POP3/SMTP e-mail client.
-  Browsers i use are Firefox on a Dell desktop and Safari on an iPad.
-  There are no rules in Settings to do auto delete (and never has been).
-  I did not accidently delete my e-mails.
-  I tried using the "Recover deleted messages" on the Deleted folder and it only brought back the last few days of e-mails that I had chosen to delete.
-  Conversation threading is disabled.
-  There is no evidence either on the Dell or in the iPad that I've been hacked - have programs in place on both machines and none have reported attacks.
-  Today, I moved what remained in my Inbox to a folder I called Keepers. 

It does appear that current activity is working correctly as mail has been coming in to the Outlook account addressed to my original webtv.net name. 

I had more than 10 years of data that I wanted to keep, including irreplaceable photos, videos and other data that are now all gone.  I don't know exactly how many e-mails were lost - my best guess would be up to 100 - 200. 

WHY DID THIS HAPPEN?!  What can you do to FIX THIS?  I'm a very unhappy customer and hope that you have a way to retrieve all of my missing data.