So my school recently made a transition from Microsoft Live to Office 365 and up until 3 days ago the transition was smooth. We had migrated for about 2 months now. Three days ago, I was able to see ALL of my emails that I kept since 2011, then when I checked for an older email I was only able to see emails since August 28, 2013. I don't know where all of my emails went! All of the Inbox folders I created are still there with their respective emails in there. 

I have called my school's IT desk and they weren't able to help, I've called Microsoft and they told me to post something online because they couldn't help me over the phone. 

I just need to know if there was a setting that I had clicked that made my inbox do this, how do I reverse it? I need my emails back!