Your notes are still there. You have accidentally turned off the switch to view them.
At the Person Tab of the People Workspace, select a fact, any fact.
Look over at the right panel for a button entitled "Options". Click on that button.
At the bottom of the menu there are two switches: Show Fact Media and Show Fact Notes. Be sure both are turned on.
Doing this for one fact turns on the switch for all facts - these are global switches.