HELP! All of my content from my game was deleted!

Everything from my game was deleted and I don't know what happened. I didn't delete them or mess with the content in any way. All of my custom content is in my Sims 3 Downloads folder on my computer, but none of it is showing up in my launcher and therefore in my game. Plus all of my neighborhoods are gone. Has this happened to anyone else and how do you fix it? Thanks in advance for any advice on how to fix this.