Lizzielilyy I apologize for the late reply; it looks like your post was only just moved here from somewhere else (or might have been caught in the spam filter). Do you still need help? If so, the next time your content doesn't load, please try deleting SigsCache inside Documents > Electronic Arts > The Sims 3.
If the content fails to load at all without reinstalling it, please instead do a clean install of all your Store content, as described in this post:
[Read First] Sims 3 Store guide | EA Forums - 11157679
The Best Practices section of the previous post (click here to view it separately) can help too, especially if you have a lot of content to install. The biggest point is that you'll need to install a few items or sets at a time to prevent things from breaking.