All my houses and sims have deleted. My computer freezes when downloading

Hi, I'm hoping someone can help me? I have had this problem for 2 weeks now and I've been trying to get in contact with EA and The Sims and I have had no help back.

PROBLEM: 

All my houses and sims have deleted except for the City Living world. My house is not showing up however, if I go on build mode, it will show up. Also, it I go to download a house of the gallery my computer will be froze for days on "Building Lot". I've left it a few days and when I download a house it says to relaunch Sims 4. What does this mean? 

I am not on a new world.

I love The Sims 4 and I have always been obsessed with playing it. However, with this problem it's made me really hate it! I hope someone can help me