These are just widgets. The data is stored in your database, and not located in any file of your WordPress install. You go to Appearance > Widgets and put whatever widgets you want into those columns. It’s possible when you were switching things around, WordPress just made them inactive.
If you’re lucky, the widgets (how you had them configured before) maybe still be available down in the “Inactive Widgets” section of the page. If so, you can just drag them back to the widget areas. If not, you’d need to obviously reconfigure the widgets.