Okay I did some research(alright I googled it) and I found the following:
In order to get your game back, follow this instructions:
1. Shut down the game
2. Go to Documents> Electronic Arts>The Sims 3> Saves, alhough the saves may be in a different place if you have an EP.
3. Say your game is called 'bob' find 'bob.sims3' and delete it.
4.Find 'bob.sims3.backup' and delete the word 'backup'
I followed the instructions and my user interface is back. Yay.
Rachel