How to play downloaded worlds?

Are the world files in the Installed World folder? It sounds as though perhaps your DCCache files are not working as they should.

How to do I find this out. :(

Normally - with houses, I just install them through the game launcher and away I go.

Is the case different with Worlds?

No, they should install just the same way as houses, but it seems that yours haven't. The DCCache files can become corrupted (so causing the Launcher to be unable to install items correctly, so I was asking whether the world files were present so that we can confirm this.

Look in Documents\ Electronic Arts\ The Sims 3\ Installed Worlds to see if the world file is there. It should be called by the name of the world you installed, for example newville.world.

"xXPerfectNeonKittyXx;c-17094784" wrote:
I have a problem. I moved my world (In this case Riverview) to installed worlds since it didn't show up, then once that didn't work I tried to rename it to riverview.world in hopes that would fix it. (It was originally named Riverview Sims 3 Pack) Once I did that, all my worlds went poof! Is there something I did wrong? Is there anything I can do to fix it?

@xXPerfectNeonKittyXx, you might be better off asking your question in the thread for new members over in the Tech section as no one has posted in this thread in a long time... :)

Here is the link for the new member thread for TS3... :)
https://forums.thesims.com/en_US/discussion/893122/thread-for-new-members-to-post-their-sims-3-game-issues#latest