Sims may have gotten stuck somehow. First thing you should try is to resetsim the bugged sim. When this fails, you can evict the particular sim (or the entire household if you like) and put them right back to the same lot.
If this doesn't fix it, you may have to load an earlier save.
I work for a living, but I don't necessarily live for a working.
Discussion - Sims 3 Game Problem
Remember, as the message said that displayed before you posted your thread...
If you're having any problem, issue, error, or glitch with your game, that's a job for MTS's Help section. There's both articles with common issues as well as Q&A support forums where you can ask questions and get specific help.
Try that first - every step, in order, and don't skip anything! Even if it doesn't say your specific problem, try it anyway, as it's a good starting point to rule out the most common causes of game issues.
If you still have trouble, you can post a new thread in the Help Q&A forums. There's a link to the Help Q&A forums at the top of every FAQ in the Help section. If you do post there, make sure to read and follow the directions that will display before you post there!