I accidentally changed my package files to open with internet explorer…

please help. I accidentally changed my package files properties for my mods and my localthumbcahe to open with internet explorer…. I now cannot figure out how to restore it back to the default app it was using…. My sims games won’t load now, in the EA app the play button for my sims is grey (and with no option to reset or reload the game)… and when I can actually get the game to load it won’t load me into any households without throwing an error and telling me to restart the game.