Custom Content not showing up in game - HELP

 My sims launcher says that all my downloads are properly installed, but once I open the game, none of them show up. How do I fix this? It's so frustrating, and it started after I accidentally checked the "Run without custom content" box. After unchecking it, the custom content still will not come back. please help!!

Its in the install content tab, however its not in the game! 
OK. If it's in the 'installed content' tab, I think the best thing to do is first try to uninstall everything and then reinstall it. 

If that doesn't work, the more drastic solution: 

- drag your 'Electronic Arts/The Sims 3' folder to your desktop 
- let the game generate a new one by starting up the launcher (or possibly the game) 

Now if you kept your old Sims3Packs in your Downloads folder, move them all from the folder on your desktop to the new folder that was just created. (If for some stupid reason the game didn't create a Downloads folder yet, you can always drag the one from your desktop The Sims 3 folder to your new one...) 
If you haven't kept them, you will need to re-download (through Purchase History and from any third party site where you got Sims3Pack content). 

Now you can reinstall all your content through the launcher. I usually reinstall in batches of no more than about 50 items, because the launcher sometimes chokes if there's more. 

If your cc works now, you can move over the contents of your Save Games, Saved Sims and Library, and if you have one, your Mods folder in its entirety, and you should have your game back. 

You might also want to copy over UserPresets.package if you have a lot of preset patterns.

That didn't work.

I had the same problem long time ago.
I tried everything!! 
BUT, as much as it doesnt have any sense at all, try to open the launcher WITHOUT INTERNET CONNEXION! Turn off wi-fi or your internet modem.
Run the game like that and check if your CC is working.
I dont know how or why, but it works for me!