Sims 3 File Types It's important to know the different file types that you'll be dealing with. Please choose which areas of our service you consent to our doing so. To provide a better website experience, hubpages. As a user in the EEA, your approval is needed on a few things. HubPages and Hubbers authors may earn revenue on this page based on affiliate relationships and advertisements with partners including Amazon, Google, and others. Other product and company names shown may be trademarks of their respective owners. Comments are not for promoting your articles or other sites. Done and done! Sign in or sign up and post using a HubPages Network account. Check each box of Custom Content that isn't installed, and then click install. When you're finished placing the files in the Downloads folder, open the Sims 3 game launcher and click on the Download button which you can find on the left. So, I moved my Sims 3 folder out and reinstalled all my Store items and custom items that were. May I found that something in my Mods folder was causing me to no longer be able to install items.